Microsoft confirmed that users of the classic Outlook application may lose access to Copilot features following the update to build 20026.20182 or higher. This issue affects customers with valid Copilot Chat licenses or paid Microsoft 365 Copilot subscriptions.
The technical glitch manifests in several ways: the Copilot icon disappears from the sidebar or the 'More Apps' section, the 'Add App' function becomes unresponsive, and commands added via the ribbon appear greyed out or unavailable to the user.
The company stated that the Copilot service itself remains operational. Users can still access the assistant through the web version of Outlook or the standalone Microsoft Copilot application while the investigation into the root cause continues.
According to the official support documentation updated on September 15, the problem stems from the application's inability to locate the PR_PROFILE_USER_SMTP_EMAIL_ADDRESS_W property within the MAPI configuration data. Microsoft has not yet announced a fix or a timeline for resolution.
