Charge 6 - Sleep score missing

[cawauk]

I've been battling to get sleep analysis from my Charge 6 for the last month. 50% of the time I get sleep stages and scores, and 50% of the time the simple timeline.

At first, I tried placing the Charge 6 in different locations on my wrist, outside, inside, right arm, but I was still getting 50% success rate.

So then I downloaded Fitbit's json files containing heart rate records and analysed 500k data points, which showed that my Charge 6 is correctly measuring my heart rate with a sufficient amount of confidence. Nights where no sleep score or stages were being provided showed better quality data than nights that would provide me with a sleep score. So another theory discounted.

Finally, yesterday, I woke up, opened up my fitbit app, pulled down to sync data and once again, no sleep score. Now here's the strange thing... I closed my eyes and went back to sleep for 20 minutes, woke up a second time, reopened the app, pull down again to resync, and to my surprise a sleep score with deep sleep analysis now suddenly appeared for the entire night.

So what's going on here?

This clearly demonstrates the data downloaded is good enough to provide sleep scores and stages, but the app (or google's cloud processing) can't correctly decipher the data? Why would 8:30hrs of continuous sleep not provide a sleep score and stages, but sleeping an extra 20 mins suddenly trigger the full analysis?

Moderator edit: updated subject for clarity

[ManuFitbit]

Hi @cawauk. Good to see you participating in the community forums. 

Thank you for taking the time to share this information regarding your Charge 6. 

As a first approach, please confirm that you are using the latest version of the Fitbit app. 

In addition, make sure that you are not having difficulties to sync: How do Fitbit devices sync their data?

In addition to that, please let me know if you are missing any other data like heart rate or steps.

[cawauk]

I'm using the latest app. I can see there's a direct correlation between charge 6 not collecting breathing rate and the missing sleep data. I.e. when breathing rate is missing, there's no deep sleep analysis. So how is it collecting breathing rate? Why is this needed to assess sleep cycles? And more importantly, why would sleeping 8 hours and waking up to check sleep (after syncing the full night's sleep) not yield results but then snoozing an extra 20 mins after this, then resyncing, suddenly produce all data for a full 8 hours and 20 min sleep? Something odd going on with the app.