I haven't had that exact problem. On iOS and macOS, a new session from idling a long time often won't start playing the last track, saying it can't find it. A

I haven't had that exact problem. On iOS and macOS, a new session from idling a long time often won't start playing the last track, saying it can't find it. Another annoyance is when someone edits the playlists or licensing situation may have changed, and songs just drop out of existence, so you never really "own" anything and there's zero permanence. It's better to have your own collection and use Spot, Last or Panda as discovery mechanisms.