I'm curious if anyone else is experiencing this...
f I start an activity and then hold down the "Down" button to go back to watch face/widgets...I always lose GPS signal and connections to any ANT+ sensors. Because when you go back into the activity, a few seconds later it notifies that GPS has been found and reconnects to my sensors.
I also noticed, sometimes during a walk activity, it randomly goes back to the watchface which is annoying because I lose GPS and won't notice until I go back into the activity.
I reported this to the beta firmware team when I was trying out the betas, even though I've experienced it since having 2.9 public release and now on the latest firmware.