Using classic Outlook for Windows in business environments
You can try to review AI's recommendations first, as it covers the currently known issue with Copilot disappearing from Classic Outlook and the workaround Microsoft has provided.
For additional information related to the points mentioned in AI's answer, please refer to:
Create a profile in classic Outlook for Windows | Microsoft Support
How do I clear my Outlook cache? - Microsoft Q&A
As an additional troubleshooting approach, it may also be worth checking a few environment-specific factors to rule out anything unique to the affected device or organization:
- Outlook version and build: Verify the exact build under File > Office Account > About Outlook. This helps determine whether the issue started after a specific Outlook update.
- Scope of impact: Check whether the issue affects only one user or multiple users in the tenant. If multiple users are experiencing the same behavior, that may point to a service, policy, or update-related issue rather than a local Outlook problem.
- Licensing status: Confirm the user still has the appropriate Copilot license assigned and that the license is fully provisioned in Microsoft 365.
- Microsoft 365 Apps update channel: Verify whether the device recently moved to a different update channel or received a recent Office update around the time the issue began.
- Office policies and add-ins: If your organization uses Group Policy or Cloud Policy, review whether any recent policy changes were deployed that could affect Copilot features or connected experiences in Office applications.
If these checks do not reveal any configuration or licensing issues, and Copilot continues to function normally in OWA, PWA, or other Microsoft 365 apps, that would further support the conclusion that the behavior is related to the Outlook-specific issue already mentioned by AI's recommendation rather than a problem with the user's account.
In that case, the next step would be to collect the Outlook build number, confirm the scope of impact, and monitor for updates or fixes from Microsoft while using OWA or New Outlook as a temporary workaround. Please let me know the Outlook build and whether the issue affects other users in the organization. Those details may help identify whether the behavior is associated with a specific Outlook build, device configuration, or a broader environment-wide issue.
I hope this information helpful and look forward to your response.