I'm hoping someone can point me in the right direction because the technician I worked with at Microsoft for almost 3 hours could not.
I manage a tenant that has 3 Microsoft add-in's (I guess they are called integrated apps now) enabled: Report Message, Find Time, and Message Header Analyzer. All deployed without issue in the console and they are viewable within OWA.
However, none of the Outlook M365 Business clients can see them. I was able to track this down in the event viewer:
The Exchange web service request GetAppManifests failed. The error code is 0. HTTP Response Code: 403
Additional Error Message: An unknown internal error occurred. The error code is 80004005
I'm not coming up with much when doing a search but it appears as though Outlook is trying to download the apps but is getting denied. So I'm assuming there is a permission error somewhere. Does anyone know where it's going, how I might be able to view more of the error, and perhaps know if it is a tenant wide setting? Are they deployed via EWS?