Using the New Outlook for Mac for personal email and calendar
Looks like this is a known issue. See the Comment by "Courtney Matthews Sep 6 2026" in https://learn.microsoft.com/en-us/answers/questions/5994694/copilot-missing-from-outlook-for-mac-after-softwar
I just finished a chat with support; there is a known issue with entitlement synchronization that the engineers are working to address. Hopefully, we'll have a fix or more information soon.