Fitbit Charge 2 heart rate accuracy during high intensity training

[ShakeNBakeUK]

Hi folks, just wondering if anyone has any experience getting their Fitbit Charge 2 to give accurate readings whilst doing HIIT. I am getting some really weird readings from mine. I am a ~30 year old male and after a sustained sprint, my heart rate is pretty much maxed out doing ~3 beats per second, yet my Fitbit is saying I am in the "fat burn" range (which I know I am clearly not). 

I have tried the following:

1) Turning off sensor, syncing, setting sensor to auto, syncing.

2) Cleaning sensor (doesn't appear to be damaged or dirty). 

3) Restarting the Fitbit whilst plugged in to USB. 

4) Keeping my wrist and body still for 10-30 seconds after a sprint before checking the reading.

5) Tried it in a variety of different positions / tightness / looseness etc. 

but none of it really helps.

The readings can be as ridiculous as 80-100bpm when my heart rate is clearly 150+

???

:S

edit: My wrist is a bit hairy - is it possible that that could be interfering? I don't sweat much if at all cos it's in an ice rink so yea 😉 I did try wearing on underside of wrist briefly but it didn't seem to help either. 

[Kizzim]

Im having the same issue. My HR will read 160 on the treadmill (just walking) then I’ll put my arm up on the treadmill and it goes down to 130 (more accurate). I’ve spoken to a person at Fitbit and they suggested to restart it. I’ll try again in the morning and see if it helped. If not they said to email them back and they’ll look for more resolutions personally. So hopefully this helps! 

[SBenn99]

Having the exact same problem, I’m very in tune with my BPM even without the use of a tracker, my Charge also loses my heart rate all together many times during a workout.