Comment 54 for bug 1521987

(In reply to Eugene Crosser from comment #25)
> It happens when audio control application running and not running likewise,
> but desktop's audio widget in the panel is indeed running (Cinnamon and
> Unity, same manifestations). It is possible that this audio widget is indeed
> the culprit.

It's possible, but I don't think it's likely.

Can you attach a log file that shows what happens when you start with analog output selected and headphones plugged in, and then unplug them and plug them back in? Instructions for getting the log: https://wiki.ubuntu.com/PulseAudio/Log