I'm using MPMusicPlayerController - ApplicationMusicPlayer with the "play audio" background mode enabled under Capabilities. When I load and play an iTunes Music track with the applictionMusicPlayer the audio stops when the screen locks or the app goes into the background. My test app also plays bundled audio simultaneously, and that audio continues playing when the screen locks but not the Apple/iTunes music.
The issue is in all the betas I've tested.
Has anyone else encountered this? Is there a new option that would affect this or is this just an iOS 13 Beta bug?
For any interested Apple devs there is a sample app submitted through Feedback Assistant demonstrating this bug. (FB6946855)