Microsoft 365 Alert – Service Degradation – Microsoft Copilot (Microsoft 365) – Users’ Copilot for Sales add-in may not appear on Outlook mobile and Outlook for Mac clients – RESOLVED
17/03/2026 08:47:00 AM
NHSmail Reference: INC46774733
Microsoft Reference: CP1253444
Issue Status: RESOLVED
Issue Description: Users’ Copilot for Sales add-in may not appear on Outlook mobile and Outlook for Mac clients.
More info: This event is related to a known issue with Microsoft Office add-ins, as explained in the following public documentation under “ISSUE: Intermittent failure to load or deploy Office Add-ins due to Exchange authentication changes”:
Final Update: 21/04/2026 08:44:00 AM–Microsoft has completed our investigation and determined the persisting impact observed by some affected users resulted from two factors. A change in the deployment procedure for the Sales add-in may have resulted in some admins who deployed the add-in to their organizations previously encountering impact due to needing to redeploy the updated version of the add-in. Additionally, users on older versions of Legacy Outlook for Mac experience, which is scheduled for deprecation in October 2026, may have encountered persistent impact, due to conflicts with the latest version of the Sales add-in. They have verified through testing with a subset of impacted users that admins who have ensured their organization has been updated to the most recent version of Outlook for Mac, 16.107 or later, and have subsequently re-deployed the Sales add-in to their organization, can avoid further impact associated with this issue.
Scope of impact: Some users attempting to view their Copilot for Sales add-in on Outlook mobile and Outlook for Mac clients may be impacted. This section may be updated as our investigation continues.
Root cause: Conflicts between changes rolled out with the latest versions of the Sales add-in and users on Legacy versions of Outlook for Mac resulted in impact.
Next steps: Microsoft are proceeding with further analysis of the involved version conflicts and deployment procedures to ensure we’re able to prevent the potential for similar impact in the future
