Hi guys, I just want to know if you have the same issue like me with your Apple Watch heart rate monitoring. AW (S2) measures HR quite well when I am resting. However, as soon as I start a workout (running) it happens many times that AW can not show HR value (greyed out), or it shows about the half of my real HR. Of course, it fit well, not too tight, not too loose, no tattoos, etc. Issue also continues after workout, while AW is measuring resting HR. In the example below I am after a 20 mins of running, and it is impossible that my HR can decrease by 98 after 1 minute (from 157 to 59 BPM). http://kephost.com/image/J90i Any idea? Should I return my AW in warranty? I have heard that Apple defines it as improper wearing..