Low HR readings during running activity?

All,

If you have concerns with the heart rate readings from your watch, please see the link below for troubleshooting:

The Heart Rate Sensor on My Garmin Watch Is Not Accurate

Specifically mentioned here is troubleshooting for users who may experience cadence lock or a low heart rate reading at the beginning of an activity.

During a 5k parkrun this weekend, I received abnormally low HR readings. It averaged 78bpm when a run at that exertion level normally averages +/-155bpm. Removing the watch from the wrist, wiping the sensor, pausing the activity, all made no difference. It was far from cold, +20°C.

Runs subsequent to that one have been recorded correctly with realistic HR readings.

Software v14.13

https://connect.garmin.com/modern/activity/10443983384

Same here,

tried all the troubleshooting, but no luck
especially on the easyruns, where it should be +/- 125 ...

Running cadence +/- 175: heart rate shows lower values way, so not 'cadence lock' issue.

Took the watch off (bpm was > 150), after that values way too low

Did nothing: values way too high

It happens on a regular basis. Here is another one, during a climbing part in backcountry skiing.
There is no way my heart rate is that low while climbing. There is a clear drop at 42 minutes from 160+ bpm to 80-120 bpm, without reason. I was still climbing, and it was not easy.

Yeah thank you, we all know that already...
We are here talking about major failures, not 10% margin error.

But when wrist based heart logging loses track of the signal, it is quite common that it fails by getting double or half signal value, which is significantly wrong. It can also sometimes lock on to the cadence. My wrist based HR is fairly good most of the time, but sometimes completely out. That is the nature of the technology used. It can also happen to the chest straps, but it is a lot less common. 

Again, I think everybody in this thread is perfectly aware of this.
I have been using a Coros Pace 2 for a long time, with a less advanced HR sensor, without these kind of failure.
Finally, many of us do find the FR255 way less accurate since 13.21 firmware.
Knowing that every new firmware release currently brings more bugs than it solves, I tend to think a regression might have occured.

After 42 minutes, so you cold weather cannot be blamed.

Stuff like this never happened to me on the older sensor (245). The 255 is clearly buggy as can be seen by posts in this forum, so it is not hard to imagine that the algorithms also have bugs in them.