Graph API, returns Unauthorized : User not found

Question

Hello all,

I develop an app which uses delegate permission to read a users presence. This all worked fine while using my Developer Subscription. After it has been expired I bought the 'Azure Active Directory Premium P1' license to simulate organizational users and test my app.

I can successfully obtain an access token, but requesting the user presence (Presence.Read) always results in this error:

{"error":{"code":"Unauthorized","message":"User not found","innerError":{"date":"2024-07-22T19:49:43","request-id":"...","client-request-id":"..."}}}
flutter: 401

This error happens when I login as admin and as another user of my organization. Info: When logging in to my account I granted permission of this app for all users of my organization.

This is my Entra ID:And for my App Registration in Azure I use another email account not related to the Entra ID. Related to that ticket, no license or anything is needed for this service: https://learn.microsoft.com/en-us/answers/questions/1111512/application-registration-cost