Been using my Active 2 for a week, right after having the software updated. For the first few days I used my old fitbit simultaneously. Completely different sleep records!!! I average 1 h deep sleep according to Fitbit, and less than 30 min with Active watch. Also, it seems to be under-estimating my Hr: measures 120, when I know I'm well above when exercising vigorously, as I checked with the fitbit and the hr monitor on the bike, which show approx the same. This is definitely a Samsung issue and I'm hoping they can sort this... HR is The essential thing! Disappointed. ( and I know I'm wearing my watch right, properly placed and proper tightness). Could the SAMSUNG team please provide an answer for this!
