Most impacted customers have confirmed that Microsoft's fix has successfully propagated to their Microsoft 365 tenants, and the Add-in is now available again in Outlook/OWA for affected end-users. If any impacted end-users still report that their Add-in is missing, please instruct them to restart or reload Outlook/OWA multiple times and to try composing several new emails to trigger the Add-in. Should the problem persist, contact our Customer Support Team at: https://www.codetwo.com/company/contact. Customer Support will prioritize this issue and respond promptly. Our Monitoring and Development Teams will continue actively monitoring this situation to ensure the issue does not recur. The problem was beyond our control and resulted from incorrect data being written to Microsoft's entitlement caches due to a configuration error on Microsoft's side. According to our telemetry data, approximately 2% of end-users may have experienced this issue. We sincerely apologize for any inconvenience caused. We will be meeting with Microsoft's engineering and product groups to discuss this issue and recommend preventive measures for the future.

The incident has been resolved. The root cause appeared to be a problem with Azure AD B2C. Restarting the affected services resolved the issue. We will be working with Microsoft to investigate the cause on their end, and to improve our preparedness for similar incidents in the future.