Dear Garmin,
on my winter holiday i had in one week 3x times a problem with end activity sooner as I would.I thought, that it must be a bug. Never happend to me in 5 years.
After third case I became a clue. On the pause screen is touchscreen on. If I am wearing long sleeves, it can happen that I let this screen few minutes active (short pause) and than without looking just pushed the start button. But because of the long sleeve has the watch switched to "save" instead of "resume".
If you already turned touchscreen off in timer app for start and reset (pretty annoying, but like I read here wad) could you turn touch on pause screen aswell?
PS: thanks for solution in paused activity and double tap on light button - display doesn´t switch to 2 minutes AOD anymore.
Sincerely
Zbynek