HR not correct when doing an activity

I am also with a similar issue. Running hills at max effort, sensing hr higher than 180bpm in my wrist with my finger and the watch would give 140 for instance. Today the same issue, with heart rates at 80-110 where before for the same workout it would be mostly higher than 120 

One addition: today I rode with my bike to work. My hr was 95 bpm... totally wrong.... So it is the same with the hr issue when recording an activity while wearing the watch on the left wrist. The watch is not useful in this case... The training load and so on is completely wrong as well as the fitness numbers... Please fix it.

Same issue I faces 3 days ago: I was running a 5K course and I found out that my average HR was 150 bpm (max. 159 bpm), while I know, from the effort I gave and from my previous experience, that I should have exceeded 170 bpm.

Added information of similar issues with my runs here:

forums.garmin.com/.../what-is-going-on-with-the-hr-readings-since-14-13

I got similar issue, however when I turn my light in myroom off, it registrates me heart rate correctly. 

Same issue. When I try to read HR from my Wahoo Tickr chest strap, it either shows up as way too low (like 89) when Trainer Road shows it as 130-140, or, when running, Garmin displays HR as 168 when I am just warming up with a slow jog. It also bounces around all over the place when running, like skipping from 170 to 130 to 80 and back up to 165 in a matter of seconds. Is there a fix for this? It essentially makes this watch useless for heart rate training and race pacing if using the external HR monitor. 

Today, I ran a 5k race. Look at the attached bizarre HR chart: until 2.3 km, the recorded HR is ridiculously low. After that, it climbs abruptly to the correct values.

I have noticed this behavior quite often: at the beginning of an activity, HR is quite low; it takes about 10-15 minutes to start displaying the correct heart rate. 

I must note that I always have my FR 955 snug fitted to my arm during an activity.

Purtroppo lo rilevo anche nelle ultime uscite.questi orologi hanno una vita propria

I’m having the exact same issue. HR couldn’t go above 80 while during an activity. My watch face said it was at 100 while walking so it’s clearly a firmware rather than hardware issue. 

È incredibile come i bug appaiano casualmente non in tutti gli orologi, anche senza aggiornamento, non invidio i futuri acquirenti attratti dal 965 un po ', dovranno affrontare infinite frustrazioni.