Same problems started with my music App and unable to debug or test my app. Worked fine around a year ago. It's still iOS 12 app, so probably something has changed. When asking to import my music library, the result is that only around 20 songs are imported, rest will stay in status "Unknown" or "Waiting" forever. When trying to get my backup from iCloud, all the files having .icloud extra extension and those files are unusable. Both of functionalities does not work anymor in iOS Simulators are using those in my real device, I still have those problems. Obviously, I'm logged in my Apple Account when testing.