I hit play on an album. It queued up the 4 songs. 2/3 the way through the first song, it stopped playing. The song was 100% downloaded. The 2nd song wasn't started downloading (I have it set to download 4). The player showed that it thought it was playing (the pause button was active).
I hit pause and play and it played for a a few seconds, then paused again, same circumstance. I did this a few times and switched to Google Music, played the same album with no problem.
4.4.4 on a Moto X (2013).
This is the first time I had used 4.9.1.