Is there a good explanation somewhere of where background task identifiers are registered and how to modify these? I have entered the "Permitted background task scheduler identifiers" into my xcode target, and it is replicated automatically in Info.plist. I can run the app (which registers the identifier), move it to background (which schedules the task), and then use the debugger to test the launch ("e -l objc -- (void)[[BGTaskScheduler sharedScheduler]...").
However, if I then go back and change the identifier string in the target, plist, and app code, the debugger no longer launches the app in background. It doesn't issue any errors, but just doesn't run it. The change I made to the name is to add an "x" at the end of the string. If I change it back in the target, plist, and app, it works again just fine.