Conditional Access - Team Authentication
When targeting Teams with CA policies we have had issues with targeting both the browser and desktop /mobile app condition. Desktop client auth gets blocked and then the client reverts to web auth within the app and lets users in.
Work around is specific, additional policies. MS support explained this and asked us to log something here.
Peter Selch Dahl commented
The lack of support might be due to the missing support in Microsoft Graph for Conditional Access, which is need for some parts of Microsoft Teams.