I have seen this in a couple of other threads, but its enough of a bother that I wanted to start a new one.
I had an iPhone 4s with Spotify Premium and I had been getting an error after a track had played for a few seconds: "Unable to play track" and the track would stop. I believe this came from syncing the tracks/playlists locally on my phone. I uninstalled and reinstalled the application and turned back on Offline sync and the problem returned.
I now have an iPhone 5s that shows the same problem. I uninstalled the application and reinstalled. Once it's back on the (unsynced/online) playlists just fine. As soon as I turn on the Offline capability the tracks come back up with the Unable to play track error.
I do notice that when I sync tracks, they almost immediately download. Perhaps when I uninstall the application its leaving the local copies on the phone and when I resync the playlist, it just looks at those tracks? That could explain the issue if its syncing a corrupted track?
Any thoughts/similar situations?