Activity freeze, crash, restart after music glitch

955 Solar, 27.09. Select run activity, GPS green, launch music, press play, finds headset (Shokz OpenRun Pro), music in auto pause, start activity, tracking begins, press play on headset - no music. Go to music screen, press play on watch. Shows play, no music. Shut off and restart headset. Activity freezes, approximately 30 secs later watch restarts.

After restart, activity offers resume, which I do. Did not try to reconnect headset. Run activity had dropped data field, replaced with timer.

Don't know if watch or headset is at fault for lack of playback - normally works fine - but no way should the watch crash even if headset is ill behaved. 

Ideas?