Microsoft finally fixed that annoying bug where Copilot buttons vanish in Classic Outlook for Windows. If you’ve got a Copilot Chat (Basic) license and noticed the button missing from the navigation pane or above the ribbon — that’s the one.
The fix shipped as a service-side change on June 29. If you’re still not seeing it, restart Outlook. Or manually update: File > Office Account > Update Options > Update Now.
The symptoms were a mess. Copilot missing from the top-right area. Icon gone from the left app bar. Adding it through ribbon customization showed it grayed out. Meanwhile, Copilot worked fine on Outlook on the web and the standalone M365 Copilot app. Just Classic Outlook acting up.
Can’t update right now? Two workarounds: revert to the previous Current Channel build (16.0.20026.20168), or switch to the new Outlook or OWA.
Separately, Microsoft is investigating another Outlook issue — unexpected crashes tied to Kaspersky Antivirus. The Kaspersky Mail Checker (mcou.dll) seems to be the culprit. If you’re seeing Event 1000 with OUTLOOK.EXE and MCOU.DLL in the Application log, that’s your sign. Microsoft says contact Kaspersky support.
Two bugs, one fixed. One still being looked at. Par for the course.
