Garmin Forerunner 645(M) Getting A Major Firmware Update March 19, 2018.
Garmin has told some users that they will be releasing a new Firmware update, March 19, 2018, that fixes at least some of these bugs.
So, this is a heads up.
March 19, is Monday. If you have a Forerunner 645(M) you should connect it to Garmin Express sometime Monday evening and see if you can get the new Firmware downloaded.