Microsoft says Copilot buttons still missing in classic Outlook
Microsoft is still investigating a bug that makes Copilot buttons disappear in classic Outlook for affected M365 Copilot users.
Microsoft confirmed the missing Copilot and Copilot Chat buttons occur after upgrading classic Outlook for Windows to build 20026.20182 and higher, because Outlook cannot locate the MAPI property PR_PROFILE_USER_SMTP_EMAIL_ADDRESS_W. The issue affects Copilot Chat (Basic) and paid M365 Copilot (Premium) customers, and Copilot remains reachable via OWA, new Outlook, and the standalone app. A temporary workaround enables 'Show Apps in Outlook' under Advanced settings, and Microsoft also acknowledged Outlook crashes tied to Kaspersky's Mail Checker (mcou.dll).