I have an Apple Watch Series 2 Nike+, and have one complaint about it. The heart rate does not register, ever. I will shut down the AW, clean the sensor with a microfiber cloth, and restart it and every time I get a heart rate of 76BPM. After that it will not read my heart rate. I even changed wrists and checked with my Fitbit Charge 2 which read perfectly. So I did the express exchange through Apple and received the new AW today. I am having the exact issue except it is reading 101BPM. Are their known issues with the heart rate monitor on the AWs not reading heart rates?