Unable to view installed add-ins on desktop version of Outlook

[truchonh]

Provide required information needed to triage your issue

Add-in was installed for multiple users through the web version of Outlook. The add-in is visible and is working correctly from the web.
Some users are unable to see the add-in from the desktop Outlook app, which they normally work with.

Your Environment

• Platform [PC desktop, Mac, iOS, Office on the web]: PC desktop
• Host [Excel, Word, PowerPoint, etc.]: Outlook
• Office version number: Outlook 365 MSO (version 2407 Build 16.0.17830.20210)
• Operating System: Windows 11
• Browser (if using Office on the web): N/A

Expected behavior

Outlook add-in should be visible from the ribbon when viewing an existing email or when composing a new email.

Current behavior

No add-in are visible from the desktop app.

Steps to reproduce

1. Install any side-loaded add-in from the web interface
2. Open an email from the mail mailbox
3. Add-ins are not visible in the ribbon
   note: We are aware that add-ins can take several hours to sync-up and be available on the desktop app. This issue is open since a few weeks, therefore waiting is not the solution.

Link to live example(s)

Not applicable. It seems to be a compatibility issue since the add-in is working well for 99% of users on a variety of exchange/365 accounts and Outlook versions. Furthermore, the add-in is working for the affected user on the web app. The iossue is isolated to this build of Outlook.

Provide additional details

The session id can be provided in private.

Context

We would like to know if there is an open issue with this specific Outlook build.

Useful logs

• Console errors
• Screenshots
• Test file (if only happens on a particular file)

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