I have noticed the issue described here in a couple of threads, when I have realized the same issue for me. Which was strange because i haven't noticed it before. The difference for me was when I started to use headphones over Bluetooth.
After recording activities without listening to the music, which in my case were strength training and indoor rowing, everything was fine.
The difference came when I've bought the headphones lately and started to run outside. When I have finished I've just stopped the music and turned off the headphones. Done, battery drain.
Today I've finished, stopped the music, "exited" the Music app to watch face and went to Settings / Audio / Headphones and disconnected them. No drain after that.
I suspect the watch is just doing what it is supposed to do, that is looking for the lost connection. Maybe there's too long timeout in the SW, if any, can't say. But when I've closed the connection. It looks like it's okay.
Was that also the case for you who suffered the drain? That is, have you been listening to music riding that activity? Have you disconnected "properly"? Please try that, if you haven't, and let the forum know. Thank you.
May be this will be addressed in the new SW, promising better music experience.
