If your Fitbit's overnight numbers went blank this week, the problem is probably the app, not the tracker. Gadgets & Wearables reports that owners who updated to Google Health 5.12 stopped seeing HRV, blood oxygen, resting heart rate, breathing rate and skin temperature, and Google says it's aware of the problem and has escalated it for investigation.
The complaints cover the Charge 6, the Sense 2, the newer Fitbit Edge and Fitbit Air. What they share is the timing: the readings went missing after version 5.12 rolled out a few days ago, on devices and accounts that had been working fine before it.
In several cases the tracker kept collecting and syncing other information, and Google Health simply didn't show the vitals, so the readings themselves are probably safe. That points to a display bug in the app rather than anything wrong with the sensors.
The Fitbit Air has no screen, so the phone is the only place to see what it measured.
Signing out of Google Health and signing back in can bring the missing readings back, and so can reinstalling the app. Some owners saw their vitals return, then vanish again later. So try it once. If the numbers come back, that tells you they were recorded. Doing it over and over won't fix the 5.12 bug.
You don't need to reset your Fitbit or change any health settings. Google hasn't given a date for a corrected version of the app yet.
The Fitbit Air has no screen, so the phone is the only place to see what it measured. When Google Health drops the vitals, an Air owner has nowhere else to look. A Charge 6 or Sense 2 owner can at least check some numbers on the wrist.
This comes in a year when Google has been moving Fitbit data and features into Google Health and pushing the old Fitbit app aside. That makes the new app the one place most owners read their health data, and it's why a bug like this lands harder than it would have a year ago.
If you're affected, sign out and back in once to confirm your readings exist, then wait for Google's fix. If you were about to buy a Fitbit Air, it's worth waiting until Google ships a fixed version of Google Health, since the app is the whole interface.