This is not an isolated problem.

Also, wait 3-6 months after a new model comes out and let suckers like me sort out the problems

There were two nearly fatal problems that caused me to contact Garmin and start the process of returning it:- it crashed, repeatedly, always in the middle of runs;- the Bluetooth signal is so weak, if my arm is at my sides below the waist, the headphones cut out

It’s a good watch that had some very bad problems that were partly fixed with a couple of firmware updates

I've been wearing the Garmin Forerunner 645M for about a week now and love it