Once it’s been played, it wont play again until the bonus round is over or once it’s played after the bonus round.
I haven’t had your exact issue, but all of my friends and I had the music stop looping only on the last level when we were playing together for the first time (and only time, as of now)
I have the same issue. It plays once and stops but then it restarts again after the bonus zone.
Thanks for the report. Should be fixed in the next patch.