I bought yesterday GF2 pro. Unfortunately all sensors are not working ! No steps No HR ! Tried to reset it several times with no luck. It seems this is very common problem with the device. VERY disappointing ! I called the sellers to arrange for return ! Will buy different brand !!
I inherited my girlfriend's Gear Fit2 Pro and have noticed the same issue with the heartbeat monitoring stopping whilst recording an exercise. After trying many things this seemed to work today:
In the Galaxy Wearables app on my phone tap on RAM and then clean now. This killed auto HR process but it started being recorded in the activity. As you can see here I did this after it stopped monitoring twice:
So turns out this didn't resolve the issue and it got worse on other rides. Found a newer firmware over on XDA Developers even though the Samsung Wear app said no new updates.
After flashing this and going for a ride today the heart rate monitoring worked perfectly. Fingers crossed this has solved the issue!