Likely causes
- Health platform permission denied for the app
- Background sync blocked by battery optimisation
- Bluetooth disconnected after the app was closed
- Multiple apps claiming the same health data
- Wearable storage full of unsynced records
Quick checks
- Open the app and force a manual sync
- Check health permissions for the app
- Confirm Bluetooth is on and the band is connected
- Look for a firmware update for the band
Step-by-step fix
Force a manual sync and note whether it completes
Grant health and background permissions to the app
Exclude the app from battery optimisation
Reboot the band and the phone
Disconnect other apps from the same health platform and retest