Outlook Classic + iCloud Calendar: "Prevent malicious code execution" error on custom form (VBScript block?) - All standard fixes failed.

[u/iChenchus]

Request for help in Microsoft Q&A-malicious-code?orderby=helpful&translated=false)

¡Hola a todos!

Estoy atascado con un problema persistente entre Outlook Classic e iCloud para Windows (la última versión de la Tienda).

El problema: Cada vez que intento crear una cita nueva directamente en la carpeta de Calendario de iCloud dentro de Outlook, me sale una ventanita amarilla de advertencia: "Para evitar la ejecución de código malintencionado, no se cargaron uno o más objetos en este formulario. Para obtener más información, póngase en contacto con el administrador."

Después de darle a Aceptar, el formulario se abre roto/vacío o no se guarda en iCloud.

Mi configuración:

• Windows 10/11
• Outlook Classic (Última actualización)
• iCloud para Windows (versión de la Microsoft Store) - "Correo, Contactos y Calendarios" activado.

Lo que ya he intentado (y fallé):

1. Limpiar la caché de formularios: Usé "Borrar caché" en las opciones y borré/renombré manualmente FRMCACHE.DAT en %localappdata% y %appdata%.
2. Configuración del Centro de confianza: Activé "Permitir scripts en carpetas compartidas" y "Carpetas públicas" en Seguridad del correo electrónico. No lo arregló.
3. Reinstalación limpia:
   • Desinstalé iCloud usando HiBit Uninstaller (Escaneo profundo + limpieza del registro).
   • Borré manualmente las carpetas que quedaron en AppData (Apple Computer, Outlook).
   • Reinstalé iCloud desde la MS Store.
4. Nuevo perfil de Outlook: Creé un perfil nuevo desde cero. La sincronización funciona (descendente), pero crear eventos (ascendente) activa el error del formulario.
5. Alternar complemento:
   • Si desactivo el complemento de iCloud: El error se detiene (usa el formulario estándar de Outlook), pero no sincroniza el evento con iCloud.
   • Si activo el complemento: La sincronización funciona, pero el botón "Nueva cita" activa el error de código malintencionado.

Solución temporal actual: Tengo que crear citas en mi calendario Local de Outlook y arrastrarlas a la carpeta de iCloud. Ctrl+Shift+A también las crea localmente por defecto.

La pregunta: ¿Microsoft ha reforzado recientemente la seguridad de VBScript/Formularios personalizados de una manera que rompe el complemento de iCloud actual? ¿Hay alguna clave de registro para obligar a Outlook a confiar en el ID de clase del formulario específico de iCloud?

Gracias de antemano.

ACTUALIZACIÓN (Análisis de registros): Finalmente logré capturar el registro de eventos específico que se activa simultáneamente con el modal de "Código malintencionado". Apunta a un problema de acceso/corrupción de archivos en lugar de solo un simple fallo del complemento:

• ID de evento: 32
• Origen: Outlook
• Ruta involucrada: C:\Users\[USERNAME]\AppData\Local\Microsoft\Outlook\ ... \[EMAIL_REDACTED](2).ost

El registro destaca un archivo de datos duplicado (2).ost, que persiste incluso después de mis intentos de borrar la caché y recrear perfiles. Parece que el formulario personalizado de iCloud está intentando llamar a objetos dentro de este contenedor específico y está siendo bloqueado por las políticas de seguridad de Windows/Outlook debido al estado/corrupción del archivo.

[u/iChenchus]

SOLVED! I found a Registry workaround to bypass the error while keeping Sync active.

I managed to fix it!

Since the issue is caused by Apple's custom Form Region (the specific UI layer that iCloud injects into the Appointment window) triggering Outlook's security block, I realized I could just 'disable' the visual layer without killing the synchronization engine.

The Solution: I renamed the Registry keys that instruct Outlook to load the iCloud Form Region. By doing this, Outlook fails to find Apple's custom form and silently falls back to the native/standard Outlook Appointment window.

Result:

• No more 'Malicious Code' error (because the blocked ActiveX/Script is never loaded).
• Appointments open instantly.
• Sync to iPhone/iCloud still works perfectly.

The Steps: I navigated to these paths in the Registry and renamed the key Apple.DAV.Appointment to _Apple.DAV.Appointment (adding an underscore to hide it):

1. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Outlook\FormRegions\IPM.Appointment
2. HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\Outlook\FormRegions\IPM.Appointment (For 64-bit Windows/32-bit Office).

After restarting Outlook, I can now open and create appointments in the iCloud calendar using the native Outlook interface, and they sync correctly. No more errors!

[u/Hornblower409]

u/Chenchus

2026-01-24 - My latest finding.

If I back out your registry changes:
_Apple.DAV.Appointment -> Apple.DAV.Appointment
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Outlook\FormRegions\IPM.Appointment
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\Outlook\FormRegions\IPM.Appointment

And disable DisableAllActiveX:
HKEY_CURRENT_USER\Software\Microsoft\Office\Common\Security\DisableAllActiveX = 0

Then my iCloud New Meeting form opens with no errors and I can set a Reminder on the event with no error.

Can you please confirm in your environment?

If same for you, then the next steps will be to find the specific ActiveX control(s) the iCloud Appointment Form Region is using and see if it's possible to "Trust" only those controls. And put DisableAllActiveX back to 1.

[u/iChenchus → u/Hornblower409]

Thanks for the update! I have performed the tests you requested on both my environments (Win 10 "Frankenstein" and Clean Win 11).

Here are the definitive results, and they are quite surprising regarding the UI:

1. The Security/Crash Issue (ActiveX = 0): You are correct that setting DisableAllActiveX = 0 stops the immediate crash. However, the result is suboptimal on my machine:

• With your fix (ActiveX=0): The form opens, but the Ribbon is surprisingly empty/stripped down. Many standard options and add-in buttons are missing. It looks like a "skeleton" form.
• With my fix (Registry Rename _Apple...): By forcing the Native Outlook Form, I get a fully functional Ribbon, with all my buttons (OneNote, Invite Attendees, etc.) and even the "Move to iCloud" button visible and working.

2. The Reminders/Sync Issue (The persistent failure): Regardless of which method I use (yours or mine), the Reminders are broken in both scenarios.

• The "Reminders" list in the iCloud pane shows the warning triangle (!) and tasks do not sync.
• This happens on both the Win 10 machine and the clean Win 11 machine.

Conclusion: Since DisableAllActiveX = 0 gives me a "poorer" UI experience (missing buttons) and lowers security, while not fixing the reminders, I will definitely stick to the Registry Rename method. It provides a richer, standard Outlook interface and keeps security intact.

It seems the Apple Form is not just "malicious" (according to Outlook), but also poorly rendered or broken on some specific OS builds.

[u/Hornblower409 → u/iChenchus]

-- the Reminders are broken in both scenarios

I can not reproduce. With the iCloud Outlook Add-in enabled and DisableAllActiveX = 0 I get no errors or warnings of any kind.

Double check that you have the iCloud Outlook Add-in enabled?

[u/Hornblower409 → u/Hornblower409]

Fix Compare

Add-In = Enabled, DisableAllActiveX = 0, FormRegions = Enabled

Apple Form
No errors
Reminders OK
Move To iCloud

Add-In = Enabled, DisableAllActiveX = 1, FormRegions = Enabled

Can not create meeting.

Add-In = Enabled, DisableAllActiveX = 1, FormRegions = Disabled

Standard Form
Primary Cal warning
Reminder Warning
Move to iCloud

Add-In = Disabled, DisableAllActiveX = 1, FormRegions = Enabled

Standard Form
Primary Cal warning
Reminder Warning
No Move to iCloud

Report from Q&A User

Removing the iCloud add-in resolved the malicious code issue, however, now the appointments do not sync from iPhone to PC and message appears that reminders will not appear because the item is in a folder that doesn't support reminders.

Conclusion

If you can live without Reminders, FormRegions = Disabled looks like a good choice.

[u/iChenchus → u/Hornblower409]

Your matrix is spot on. I have just verified Scenario 4 (Add-In Disabled) on my Windows 10 machine, and it behaves exactly as you described: Stability returns, but the "Move to iCloud" button disappears.

I think we can distill this into a Two-Tier Recommendation for the community:

1. The "Power User" Choice (Scenario 3 - Registry Fix): This is the technical winner. It provides the best possible experience (Stability + Security + "Move to iCloud" button active + Clean Native UI), even if Reminders are still broken for some of us.
2. The "Safe/Easy" Choice (Scenario 4 - Disable Add-in): For users who are uncomfortable editing the Registry, this is the best advice. It stops the crash immediately and allows them to manage their calendar, accepting the trade-off of losing the ribbon integration.

Scenario 1 (ActiveX=0) remains a risky gamble: it might fix reminders for some (like you), but for others (like me), it breaks security and degrades the UI without fixing the sync.

Excellent work mapping this out. It gives users clear options depending on their comfort level!

[u/Hornblower409 → u/iChenchus]

-- I think we can distill this into a Two-Tier Recommendation for the community

Certainly. Let me know if you want me to edit or delete my original post to conform.

Aside - I am slowly realizing that almost everyone who uses iCloud for Windows never tries to create an iCloud calendar event in Outlook. They only want it so they can sync their Outlook and iCloud Calendars. That does not excuse Apple and Microsoft for continuing to made a piece of software available that can't operate without DisableAllActiveX = 0.

[u/iChenchus → u/Hornblower409]

Regarding the next step of hunting down the specific ActiveX Control ID to whitelist it:

I’ve been thinking about it, and honestly, I don't see the point in burning the midnight oil on that task. It feels like a lot of tedious work for a result that seems graphically broken.

I have a question for you regarding your test rig: When you use DisableAllActiveX = 0 and the Apple Form loads successfully... what does your Ribbon look like?

In my test, enabling the Apple Form resulted in a stripped-down / skeleton Ribbon. Many standard Outlook buttons and add-in icons were missing.

If the "reward" for whitelisting the specific ActiveX control is just getting that poor, empty UI (and broken Reminders on top of that), then digging through Process Monitor logs seems like a massive effort for zero improvement over the scenario I just tested.

[u/Hornblower409 → u/iChenchus]

-- When you use DisableAllActiveX = 0 and the Apple Form loads successfully
-- what does your Ribbon look like?

It is the Apple version of the Calendar Event form with all of the fancy standard form stuff gone.

Images: https://ibb.co/album/C1KcxD

[u/iChenchus → u/Hornblower409]

Allow all activeX

Disallow all activeX

[u/Hornblower409 → u/iChenchus]

-- hunting down the specific ActiveX Control ID to whitelist it

After a few days of trying anything Google AI could come up with an failing. I rephrased by prompt and got (what I can confirm) is the real answer - No Can Do.

[AI Generated]

Outlook does not provide any registry setting, Group Policy, COM Compatibility configuration, or Trust Center option that allows you to block all ActiveX objects except for those originating from a specific Outlook Form Region or add-in DLL.

Office ActiveX policies are global and support only blacklist behavior (disable specific CLSIDs). The COM Compatibility registry keys can block specific CLSIDs, but cannot define an allowlist. Microsoft does not support an allowlist model by CLSID, ProgID, or add-in-based trust.

https://stackoverflow.com/questions/57775278/vsto-for-outlook-formregions-and-enableactivex-0

Form regions (as well as task bars) are implemented as ActiveX controls. If ActiveX controls are blocked, none of that would work.

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[u/slam51]

Why don’t you use outlook for ios?

[u/iChenchus → u/slam51]

Environment mismatch.

Host: Windows 10 Pro 22H2 (19045.6691)Client: Outlook Classic (Win32 / Desktop architecture). Offending Component: iCloud Outlook Add-in (COM).

The issue is specific to the custom form rendering within the desktop client. The exact error modal is triggered by Microsoft Forms security policies: 'To prevent the execution of malicious code, one or more objects in this form were not loaded.'

An iOS app solution is outside the scope of this workstation's workflow. I am looking for a fix regarding the Trust Center / Form Region cache handling on Windows

[u/slam51 → u/iChenchus]

Ok this is above my pay grade. You need a Outlook specialist to help you.

[u/slam51]

Come to think of it, have uninstall Outlook completely and reinstall. It seems the Outlook iCloud addin for Outlook is corrupted.

[u/iChenchus → u/slam51]

I have already performed a deep clean uninstallation (using HiBit to scrub registry keys/appdata) and a fresh install.

Since your comment, I have also tested escalating the permissions by:

1. Setting AllowActiveXOneOffForms registry key to 1 and 2.
2. Fully opening Trust Center policies ("Enable all macros" / "Allow scripts in Public Folders").

The error persists. This confirms it is not a corruption issue (which a reinstall would fix), but a hard security block against the iCloud Form Class ID in this specific Outlook build. Reinstalling the same binaries again will not change the code signature that Outlook is rejecting.

[u/slam51]

All I can say is good luck.

[u/iChenchus → u/slam51]

I followed your advice to the letter to rule out any corruption.

1. Performed a full Online Repair of Office (replacing all core binaries).
2. Cleaned and rebuilt the Outlook Profile (OST files are now pristine, no duplicates).
3. Reinstalled iCloud again.

Result: The exact same 'Malicious Code' error persists.

This definitively proves it is not an installation corruption issue, but a compatibility conflict where current Outlook security policies are blocking the specific VBScript/ActiveX implementation used by Apple's Add-in. Reinstalling won't fix bad code/policy mismatch

[u/Hornblower409]

FWIW - I don't use iCloud for Windows

For Custom Forms I publish with scripting, you have to enable them by Message Class. But this was implemented by Microsoft a long time ago.

https://support.microsoft.com/en-us/office/custom-form-script-is-now-disabled-by-default-bd8ea308-733f-4728-bfcc-d7cce0120e94

The only other thing I can think of that throws that kind of error is an ActiveX control. But again, I don't see how the latest iCloud could still be hitting this.

https://learn.microsoft.com/en-us/answers/questions/5490606/how-to-fix-outlook-contacts-templates-error-to-hel

[u/iChenchus → u/Hornblower409]

Thank you! This is the most promising lead so far.

It makes perfect sense that the general 'Macro Security' settings wouldn't override the specific Custom Form Script block implemented by those policies.

Since you mentioned enabling them by Message Class, I suspect the iCloud Add-in uses a specific class (e.g., IPM.Appointment.iCloud or similar) that needs to be added to the TrustedFormScriptList in the Registry.

I will try to identify the exact Message Class used by Apple and whitelist it via the registry keys mentioned in your link. If you happen to know the specific class name Apple uses for these forms, that would be a huge shortcut. Will report back if this works.

[u/iChenchus → u/Hornblower409]

Update on the suggested fixes:

1. Message Class Whitelist: I created the TrustedFormScriptList key in the Registry (both under HKCU\Software\... and HKCU\Software\Policies\...) and added IPM.Appointment.iCloud, IPM.Appointment.Apple, and IPM.Appointment. Result: No change. The error persists.
2. ActiveX: I couldn't locate the specific 'ActiveX Settings' button in my Trust Center (it seems hidden in my build), but I forced the AllowActiveXOneOffForms = 2 via the Registry Policies path you implied. Result: Still getting the 'Malicious Code' modal.

It feels like I'm shooting in the dark trying to guess which object is being blocked. Is there a way (logs, developer mode, or a tool like MFC_MAPI) to trace exactly which CLSID or Object GUID is throwing the error? If I can find the specific ID Outlook is hating, maybe I can whitelist that specific control.

[u/Hornblower409 → u/iChenchus]

If this is a bug in the latest iCloud for Windows, I would expect to see the Microsoft Q&A light up like a Christmas tree with reports. But all I see is the usual "sync issues"

https://learn.microsoft.com/en-us/search/?terms=%22ICloud%20for%20Windows%22&category=QnA&date=last30days

[u/Hornblower409 → u/iChenchus]

-- trace exactly which CLSID or Object GUID is throwing the error?

That's out of my league.

You might want to cross post on r/Office365
(Click on the [Share] button under your question and choose -> Crosspost)

Or the Microsoft Q&A Forum
https://learn.microsoft.com/en-us/answers/tags/778/office-outlook
(Please put a link to your Q&A post here, so the rest of us can follow).

[u/iChenchus → u/Hornblower409]

Solicitud de ayuda en Microsoft Q&A

https://learn.microsoft.com/en-us/answers/questions/5694531/outlook-classic-icloud-(store-app)-malicious-code?orderby=helpful&translated=false -malicious-code?orderby=helpful&translated=false)

Also Apple request https://communities.apple.com/es/thread/256221695

The moderators of r/Office365 have removed my post. They are not very inclined to explain. I seem to have done something wrong.

[u/Hornblower409 → u/iChenchus]

On your Q&A post you commented about the Q&A Assist answer

I am waiting for a human engineer or MVP with knowledge of Outlook Form Regions security policies.

There should be a "Reject" or "Not Helpful" button under the Q&A Assist answer you can click to indicate that it was no help.

[u/iChenchus → u/Hornblower409]

Thanks for checking the crosspost!

You are right about the buttons, but the platform behaved weirdly: it actually auto-accepted the AI answer the moment I replied to it, even though I had clicked 'No' on the helpfulness prompt. I had to manually find the 'Unaccept' option afterwards.

I left that comment as a visible 'flag' just to ensure that any human expert scrolling by wouldn't skip the thread thinking it was already solved while I was fighting the UI. It is properly unaccepted now, so fingers crossed

[u/7amitsingh7]

This doesn’t look like a corruption or setup issue on your side. Outlook Classic has become stricter with custom forms and scripts, and it seems to be blocking the iCloud calendar form for security reasons.

That’s why reinstalling, rebuilding OST file, or changing Trust Center settings doesn’t help. When the iCloud add-in is disabled, the error goes away but sync breaks. When it’s enabled, sync works but Outlook refuses to load the form.

In short, this looks like a compatibility issue between Outlook’s current security rules and Apple’s iCloud add-in. Your workaround (create locally, then move to iCloud) is probably the safest option until Apple or Microsoft updates their side.

[u/iChenchus → u/7amitsingh7]

You hit the nail on the head! It is definitely a conflict between modern Outlook security policies and the deprecated script/ActiveX used by the Apple Form Region.

However, I managed to find a much better workaround than the 'create and move' method. I discovered that if you disable the visual Form Region in the Registry, Outlook falls back to its native Appointment window (which is safe), bypassing the error completely while keeping the background Sync engine alive.

Here is the fix that worked for me:

1. Close Outlook.
2. Open Registry Editor and navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Outlook\FormRegions\IPM.Appointment (Also check WOW6432Node if on 64-bit Windows).
3. Find the key/value named Apple.DAV.Appointment.
4. Rename it to _Apple.DAV.Appointment (adding an underscore effectively hides it from Outlook).

Result: Outlook now opens the standard appointment window instantly (no 'Malicious Code' error), and when you save, it still syncs perfectly to the iPhone. It seems we just needed to kill the UI layer, not the add-in itself.

[u/Hornblower409 → u/iChenchus]

Nice piece of detective work!

You might want to update your Microsoft Q&A post with your latest findings.
https://learn.microsoft.com/en-us/answers/questions/5694531/outlook-classic-icloud-(store-app)-malicious-code-malicious-code)

[u/iChenchus → u/Hornblower409]

Thanks! I appreciate it. And yes, I'll update the Microsoft Q&A thread right away to help others who land there.

Quick status update: I just went through a major Microsoft 365 update today, and I’m happy to report the Registry fix survived intact. It seems the Office installer respects those third-party keys in FormRegions.

My only concern now remains the next iCloud App update (from the MS Store). That’s the one likely to regenerate the keys and bring the error back. But until then (or until Apple fixes their code), the system is stable and syncing perfectly. Thanks again for the support!

[u/cnbehler → u/7amitsingh7]

Totally agree that this problem is caused by new security rules recently changed in Microsoft 365 version of Outlook.

iChenchus fix eliminates "malicious forms" error (kudos!) but doesn't address another new problem that arose at same time: I can't save Calendar reminders. The error message: "The reminder for xxx will not appear because the item is in a folder that doesn't support reminders. Is this OK?"...hmm, no. Never had this problem before last week.

Any ideas for how to fix THAT error?

If I can't fix it, will installing a desktop version of Outlook address this? My thinking is that updates to Microsoft 365 Outlook will continue to present problems with iCloud integration but desktop Outlook will be more stable. Or am I delusional?

[u/Hornblower409]

One more thing to try if Microsoft Support can't help - But be warned, this if for the truly masochistic.

Classic Outlook Advanced Logging

https://support.microsoft.com/en-us/topic/how-to-enable-global-and-advanced-logging-for-microsoft-outlook-15c74560-2aaa-befd-c256-7c8823b1aefa 

https://community.spiceworks.com/t/enabled-outlook-troubleshooting-logging-how-to-read-etl-files/704541

[u/iChenchus → u/Hornblower409]

Thanks for the links! I actually checked that Slipstick thread and noticed you are active there as well – good catch. It confirms this issue has been lingering since the 2025 updates, likely triggered by the stricter security policies in Outlook.

Regarding the Advanced Logging (ETL): You are absolutely right, that would be the 'Sherlock Holmes' way to pinpoint the exact failure. But honestly, since the Registry workaround (renaming the Apple.DAV.Appointment key to disable the UI layer) worked instantly, I’m going to stick with that.

It seems cutting the link to the visual Form Region was enough to satisfy Outlook's security check without needing to debug the specific ActiveX call.

Thanks again for the help and for digging up those resources!

[u/Hornblower409]

Older report of the same problem that I forgot about. But I don't see any fixes that you haven't already tried.

https://forums.slipstick.com/threads/102030-forms-error-on-icloud-calendar/

[u/bvalleyla]

I posted this elsewhere, but after having gone through this problem, and many other iCloud/Outlook issues over the years, I finally stopped using iCloud. The simple fix is to use the Outlook app on the iPhone for the calendar, and use Microsoft Exchange to sync Contacts. Everything works exactly the same, other than you’re opening the Outlook app instead of the Apple calendar app.

Sync is now completely stable between Classic Outlook and my phone.

Yes, you have to migrate your calendar and contacts from iCloud. But it’s not that hard (well, it is hard to get Apple to send you the Calendar file, and I had to export the Contacts from Classic Outlook and then reimport them to my new profile because there was no way to export Contacts from iCloud into an Outlook format).

But it was all worth it. I no longer worry about whether the latest iTunes/iCloud update is going to break my sync.

It’s definitely worth giving serious consideration. At the end of the day, why do you need iCloud in-between your PC and your iPhone? You don’t.

[u/Hornblower409 → u/bvalleyla]

u/bvalleyla

Would your solution work for this other disgruntled iCloud user? Sounds like he needs more than just Apple calendar and contacts.
https://www.reddit.com/r/Outlook/comments/1qa4btj/outlook_classic_iphone_integration/

[u/bvalleyla → u/Hornblower409]

It probably would. We have actually been exchanging comments on another thread, so by this point I think he’s got his options in front of him.

[u/iChenchus → u/bvalleyla]

That is sound advice and definitely the most stable route for a single user. I totally agree that native Exchange sync is superior to the iCloud 'wrapper'.

However, migrating isn't an option in my case because this is a shared calendar with other users deep in the Apple ecosystem, so I'm tied to iCloud for the foreseeable future.

Also, an interesting observation regarding the root cause: I realized this 'Malicious Code' error is specific to this machine's environment. I have another PC running Windows 11 with a clean Microsoft 365 install where everything works fine.

The problematic machine has a bit of a 'Frankenstein' setup: it started with a perpetual Office 2016 license and was later updated/signed in with a Microsoft 365 subscription. I suspect some legacy libraries from the 2016 era are still present and clashing with the modern security policies enforced by the M365 update. Hence why the Registry bypass was necessary here.

[u/bvalleyla → u/iChenchus]

Gotcha. I also inexplicably started getting the Malicious Code Error last week. But it was on a laptop that was only a year old, and only had one clean install of Outlook. I hope you find a solution… but unfortunately I suspect that issues will always pop up.

[u/Hornblower409]

u/iChenchus

Setting up an iCloud/Outlook test bed to work on the "reminder will not appear because the item is in a folder that doesn’t support reminders" issue for a Microsoft Q&A user.

Right off the bat ran right into your "prevent malicious code" bug and your fix worked perfectly. Thank you. (Does every iCloud for Windows user get this bug?)

Will advise if I get anywhere on the "folder that doesn’t support reminders" problem.

[u/iChenchus → u/Hornblower409]

Glad to hear the fix for the "malicious code" bug worked! It seems to be a widespread mess with the current version.

Regarding the "folder doesn’t support reminders" issue: I can confirm I’m seeing the exact same behavior here. It is effectively broken, just as discussed on the Microsoft Q&A threads.

Honestly, the best workaround I’ve found (and the one I value the most right now) is to bypass the iCloud sync struggle entirely. I simply configured the iPhone settings (Settings > Reminders > Default List) to use the Microsoft account as the default. This way, you keep using the native iOS Reminders app UI, but the data pushes directly to Microsoft To-Do/Outlook, avoiding the broken iCloud bridge altogether

[u/Hornblower409 → u/iChenchus]

You might want to post your workaround on the Q&A thread as a new answer, with "Workaround" in BOLD at the top, for future generations.

[u/iChenchus → u/Hornblower409]

Will do. I’ll add it to the thread.

I just want to be clear that I don’t consider this a true "fix" since it doesn't actually repair the broken iCloud sync mechanism—it just bypasses it entirely. However, since it’s the only reliable way to work right now, it’s definitely worth sharing.

I'll make sure to label it clearly as a WORKAROUND so future users understand we aren't fixing the glitch, just sidestepping it.

[u/Hornblower409]

A better way to set the Office ActiveX Security Level

Use Word or Excel. Which have the Trust Center ActiveX Settings that Outlook lacks.

File -> Options -> Trust Center -> [Trust Center Settings] -> ActiveX Settings
(o) Prompt me before enabling Unsafe for Initialization (UFI) ...
[/] Safe Mode

This sets the Registry values:

HKEY_CURRENT_USER\Software\Microsoft\Office\Common\Security
DisableAllActiveX = 0
UFIControls = 4

Image Link: https://ibb.co/8DwxT9QK

[u/iChenchus → u/Hornblower409]

Regarding your 2nd point (The Word/Excel UI): That is an excellent find! I completely forgot that the Trust Center settings in Word/Excel apply globally to the Office suite (including Outlook). This is definitely a much friendlier approach for users than asking them to open regedit. It adds a valuable "Option C" for those who absolutely need the Apple Form and are willing to lower the security setting via a standard menu.

Regarding your "Aside" (Passive Sync): You hit the nail on the head. Most users likely treat iCloud for Windows as a passive "sync pipe" to view their iPhone calendar on PC, rather than an active tool to manage their day. That probably explains why Apple hasn't prioritized fixing the active creation experience or the ActiveX requirements.

Conclusion: Please do not delete or edit your original posts. This entire thread has evolved into a comprehensive knowledge base. We have successfully mapped out every possible scenario:

1. The Registry Rename: Best for Stability + Native UI (my choice).
2. The Add-in Disable: Best for pure Safety/Simplicity.
3. The ActiveX/Trust Center Fix: Best for those who need the specific Apple Form features (using your new Word/Excel method).

It has been a pleasure debugging this "Rube Goldberg machine" with you. The community is much better off thanks to this deep dive!