Low HR at the start of an activity, also in FW 21.19

21.19 has not solved it for me either. 

Still experience OHR issues during the first 20 minutes. 

Today a run where it took 31 minutes to get the right heart rate.

Will do some more runs, as I've the feeling something changed in OHR

During warming up, the HR seems to be OK, after auto stop/start HR was rubbish again.

Will share the chart once I'm using my computer. 

I am really sad to see it is still not fixed.

Same here. How can such a basic feature be rendered completely useless. 

I recently upgraded from a Venu 2 to a Forerunner 955. I have regularly seen this problem with both watches - not surprising as they have the same Elevate v4 heart rate sensor.

It seems to have appeared (or got bad enough to notice) several months ago, and seems significantly worse on the FR955.

On the Venu 2, the recorded heart rate would often be far too low for up to the first 7-8 minutes - often 30bpm or more - and suddenly jump up to a realistic value.

On the FR955, the same happens but for my last two activities (a run and a walk) it took 13 minutes and 24 minutes to jump to the correct value. For the walk, it recorded values as low as 72bpm for several minutes, even though I was walking at 6km/h.

I've seen the heart rate appear to fall drastically when I start the activity.

The Forerunner 955 is fully upgraded to the latest 21.20 software (and the Venu 2 was also updated to the latest release).

I appreciate that wrist-based heart rate sensors are not that reliable or accurate, but I'm sure this used to work better in my early days with the Venu 2.

yup, Garmin seems did it on purpose without accountability to fix it for the user who has the problem, they thought as long as the majority (more than 60%) is not affected, no need to fix it. and here they are, locking the threads without solution and just told user to use the warranty service with local store, but some of us is already out of warranty with out watches. Shame but i'm already saving up for my Coros Pace Pro, abandoning my unuseable 955 Solar.

Absolutely, I will switch to Pace Pro as well. Accountability for their actions is the basis that I require from the company.

I have the same problem, the 955 is relatively new and got the latest firmware update, 
garmin has really bothered me with products that don't work properly after every update. 
I am also experiencing various issues with the sensors being lost on the garmin 1040 solar as well. 
Please if it reads there on garmin, fix the problems!

I have the same with the latest update...before was relatively everything fine...latest trail uphill run i felt i was around 150-160bpm and 955 shows me 110

Normally i wear chest strap but i wanted to test the latest firmware only by measuring by watch itself...

I did another run today and the same problem occurred again. The watch didn't lock on to my heart rate for the first seven minutes of a run at 6.25min/km, and completely missed an interval of 4.4min/km. After 1km, it told me my performance condition was "+8", which was clearly nonsense based on the incorrect heart rate.

After the run, the watch told me my lactate threshold had increased, but it's hard to know if this is real or because of the faulty recording.

The problem is easy to see in the graph below - grey is heart rate, blue line is pace.

The same here, the first cycling 5k cycling in broadcast mode is not shown.