[AC Question]

So I've had my GS4 for a while now, and in the last four months or so the music player controls (pause, track skip, etc) have stopped appearing on lock screen. They'll appear sometimes, but after a few minutes they vanish, and I have to unlock my phone to skip tracks. I have PIN security to unlock, but I've never put a widget there to use the music player, nor removed one -it's always worked on its own since I bought the phone. I thought for a while it was that I'd switched to Nova Launcher, but removing that proved it wasn't the case. So I've tried removing Nova/reverting to TouchWiz launcher, changing the lock screen security settings, using a different player (power amp), and even using a lockscreen app, but none of it works. Anyone? I'd love to be able to switch songs without unlocking the phone every time, and since it worked before, this is ultra annoying.

Thanks in advance.