I own a forerunner 255 non music version which I wear 24/7 and I've noticed in the two weeks I've owned the watch that whilst wearing it at night during sleep, occasionally it fails to record that nights HRV status. So far over that 2 week period there have been 3 occasions when it has failed to record overnight HRV.
Ive had answers from folk over on the 255 forum that is being seen across a few units but is the same behaviours being seen on the 955?
forums.garmin.com/.../nightly-hrv-status-periodically-not-recording