SOLVED: In the .entitlements File there was a record Missing: Key: App Sandbox Type: Bool Value: YES Somehow according to some tutorials this entitlement needs to be added in order for the cloud sync to work.

Hey Same Issue here, However with xcode Previews (simulator and also real device) the transaction works perfectly. Only in my first testflight distribution (internal i get the error)

Tre transcactin seems successful at first (shows blue checkmark), the problem seems to occur, whilst validating the transaction. Is it possible that It could have something to do with receipt validation? This should be completely handled by storekit 2 itself, however I have read in other forums, that it might need to be done manually... I hope not. Im Running the Beta version of the app on my iPhone 13, and signing in with personal Apple ID for the purchase (No sandbox user or anything)