gingpete retracting my previous statement, it doesn't sound like the same bug, it might be something your doing incorrectly your side. Have you included .m4a versions of your music? I've never run into any file size limits myself.
Also, music isn't perfect in that it will only begin playing on touch end. Consider it like queuing up the sounds with the construct 2 actions instead of it playing. There are a couple of work arounds such as playing the music silently on a loading layout first. Still experimenting on the best option, though it's also different for most games.
— is a stable release containing this audio fix planned any time soon? Thanks for all the help!