I just got the new Gear Watch 4 days ago and in two instances during vigorous activity it appears to lose track of the heart rate and other sensor features like the stress level. Having used other trackers in the past I tried to reposition the watch on my wrist and that didn't do much. I like to see my heart rate during runs. I would think this sholdsstay on. I do have the sensor set to stay on all of the time in the settings as well.