I experience a loss of CMDeviceMotion events (using iOS13.1.x, not tested with ealier releases) initiated using startDeviceMotionUpdatesToMotionQueue() once the app enters background and returns to foreground. The deviceMotionUpdateInterval is set to 100ms.
devicemotionData no more occurs. A re-initialisation of CMDeviceMotion is required to recover.
My App generally supports location updates in background mode, which seems not a sufficient setting.
Any hint? Is HealthKit's HKWorkoutSession the only way?