I have a Galaxy III running JellyBean (4.1.1) and Google Music 4.4.811H.526848
I played Google Music ("Play Music" icon) alot in Sept-Nov with no problems. I did the Verizon update to JellyBean in December, and have not tried to play music since then. I started playing music with the Play Music icon this week and it keeps hanging. I see this on streaming music as well as music local to the device. It will play a few songs correctly, then stop playing when moving to the next song. When this happens, the progress bar for the song stops moving, but otherwise the app appears to be working. The pause icon is displayed, which is what i normally see when music is playing, I can move back the view to see all the songs in the album and the equalizer graphic is moving up and down. The only way I have found to get it working again is to restart the phone.