I use my phone a portable music player whilst walking back and forth from work. Having moved to a phone that comes with Windows 10 Mobile, I've found that playback will pause for no apparent reason. Sometimes it'll be a few seconds after I've locked the screen, sometimes it'll almost straight after starting playback.
The songs are stored on the phone's internal memory, so I doubt it's related to buffering problems, but what be causing this? Is it just a shockingly bad bug to be present in this initial release?