Bug valid for iOS 17.7.2 on iPad (not valid on iOS 18.1.1 on iPhone).
Using those simple wired Apple headphones. Playing a beat in BeatNote. Fine. Gesture change to other app which is using sound (here: playing a score in UltimateGuitar, but other sound-using apps too). Gesture change back to BeatNote. Hit play. No sound. Uuuuuuurghhh. Unplug headphone cable and replug headphone cable. Hit play again in BeatNote: sound. Best regards, Jörn.