Heart Rate Accuracy Issues with Fenix 8

So this problem is still unresolved? If core functions dont work, the watch is useless.

Hi matej787 and everyone

There have been numerous updates and I have the feeling that the problem might be solved, at least with my watch.

Based upon a couple of runs, I haven't seen any discrepancies anymore. I will test this more thoroughly in the next couple of days to see if the situation is stable.

Did anyone else notice an improvement?

Hi,
So I returned my Fenix 8 and received a new one, this one has behaved so much better, but as you say it could be a software update.
What I am now seeing is a difference between the watch and the app's recorded activity.
So I go on a long walk, I'm constantly checking my heart rate on the watch and it never goes above 101.
On the app I see sections up to 111, but the watch NEVER displayed over 101..

@3670937

I used to see exactly the same, I returned the watch and the new one is way better.
Faulty sensors?

OK .. so i contacted Garmin few times about this .. the suggestions were to try different profiles since i only need to track my HR ... i did try the rower and cardio and they seem more accurate .. I do CrossFit so the watch moves a bit sometimes especially when using barbells and some movements that involve wrist movement which will interfere with the reading .. still better than the HIIT profile for now ... i will keep testing for some time   

for high intensity intervals, HIIT, the only thing that works is chest strap, or at least and arm band sensor, optical hr sensors cant catch the hr bpm because of its very nature, its well known in the fitness comunity, for steady and regular runs, and maybe long intervals its works very good, depends on the watch model

An arm-based optical sensor works pretty well for high-intensity workouts as well, even those with significant arm movements, if you wear it on your bicep (the sensor really sits on your shoulder).  I've tested this against a chest strap (as have many others, DCR has a whole writeup on this) and the only appreciable difference is during warmup, for the first few minutes.  Sometimes the arm reads a little low for a couple of minutes, but after that, it's within a couple of beats of a chest strap.  Seems good enough for most uses, less hassle, more comfort than the other.

I've seen this many times as well, the sampling/display granularity sometimes don't intersect.  I'm pretty sure the HR display uses some sort of weighted-average algorithm, maybe a 5-second or similar.

Garmin Netherlands has officially confirmed this is a know issue of the Fenix 8. The watch is useless for running. I returned the watch to the dealer for a refund.

since it's getting colder the heart rate bug is back.registering a unnatural high heart rate in the beginning of my run. It may also be an update that re-introduced the heart rate big. This messes up my recovery stats and VO2Max strongly. I now monitor it and stop the run when I see it going up and wait a bit. That mostly helps the problem. But this is not possible in a race so I'm still very annoyed with this way too expensive watch. I wouldn't recommend this wathc to anyone right now.