Turning on Metal API Validation, and reinstalling Xcode, seemed to work.

Turning on Metal API Validation, and reinstalling Xcode, seemed to work.

still researching... this may relate to this older thread: https://developer.apple.com/forums/thread/44637: "Sounds like you are treading the same path I went my friend. I also tried using AVAudioPlayer for music and ambient sounds. But in the end, the whole mess of AVAudioPlayer and SKAudioNode just didn't work well. And once past anything trivial, the performance of SKAudioNode is not great. ALL SKAudioNode sounds are read (streamed) from files instead of memory buffers at the AVAudioEngine level, and this starts to impact on frame rate and audio quality once you have more than a few sounds to deal with."