I ware my 945 daily. It is up to date with all the latest firmware. 4.20, etc. I have enabled the new high heart rate outside of an activity. On multiple occasions while at or near being at rest the Alarm has gone off. I initially had the alarm set at the default 100 bpm. So I increased the limit to 120 bpm. At least three times this week this alarm has triggered. I used the Garmin Connect app to monitor my heart rate and it displays over the alarm limit I have set. So all is well or not well? I manually check my heart rate and it is about 50% lower than what Garmin Connect is showing. The only way I have found to reset the heart rate is to remove the 945 from my rest and leave it on a flat surface for a minute. This seems to be a bug.