From time to time (in fact very often) my iPhone will stop displaying the lock screen "now playing" info, and subsequently the controls won't be there.
I can still start the music app playing something, but I can't pause or skip tracks.
The same thing can be seen if I try to use the multitasking audio controls (swipe "left" on the multitasking bar). The play/pause button won't stop audio playback. Can't skip.
Same problem with the headset remote buttons. Can often start audio playing (although what it'll play is random). Can not stop/pause, can not skip.
I've not been able to reproduce this reliably, but it happens often. The phone is in this state more than it isn't. A restart resolves this most times.
How to fix?