This works for me: if you're using headphones/earbuds with attached volume control, play/pause bottons . . .
Completely exit out of HyperPad and make sure it's gone from previously opened apps. Start playing whatever music you want to play. While music is playing, open HyperPad app. HyperPad should stop the music. When this happens, just wait about 2-3 seconds and press the play button attached to your headphones/earbuds.This works for me every time.