My Galaxy S4 would play, then stop after about 20 seconds. Happened with all music apps (spotify, Media players etc). The problem for me was the "Cover" App. I uninstalled the cover app and now my music plays normally again. :cool:
I had the same problem. For me it was the "airdroid notification mirror service" in the accessibility settings. I turned it off now I can get full-screen in the gallery app again.