Inspire 3 is not tracking my HRV readings accurately

[PC_UK]

Fitbit user since January. Until the last couple of weeks, HRV has been doing what you might expect - modest changes night on night, with the occasional larger spike or fall, around a range of about 20 to 30ms. From 21 September, I had a series of super-high readings (130ms and upwards) for 7 nights, and then for the last 5 nights straight it's been 0ms every night - which I frankly don't believe. 

I've tried everything short of a factory reset of my device (delete and reinstall app, restart device, clean sensor area, adjust tightness of band etc). I'm up to date on firmware and app updates. Heart rate tracking is behaving normally, so I'm thinking that this is a software / firmware issue rather than hardware problem?

Is anyone else getting anything similar? Any ideas as to solutions? I would ignore, but the absence of the HRV figure messes up the readiness assessment.

Moderator Edit: Clarified subject

[Gr4ndp4]

Hi, @PC_UK, welcome to the community. You may find this article of interest How do I track heart rate with my Fitbit device? - Fitbit Help Center In particular, you must wear your device for at least a full day, including to sleep at night. If you have deleted & reloaded the Fitbit app & updated it, this may have interrupted the process.

I hope this helps, but if you are still stuck, please post here again.

Cheers

[PC_UK]

Thanks, but I only deleted and reinstalled the app to try and fix a problem which already existed, so I don't think it can be the cause of the issue. My Fitbit had been measuring my HRV in what looked like quite a normal pattern for months. Then I had a week of sky-high readings and then it recorded a reading of 0ms for 5 nights straight - which is biologically impossible. I'm guessing someone behind the scenes has been messing with the algorithm used to derive HRV from the heart rate measurements...