Not all heart rate data sync

Hi

For a few days I’ve got a Forerunner 45 watch connected to my iPhone

Watch OS is 5.40 and Garmin Connect version 5.6.0.22

At the beginning everything was working right, but now syncing is not automatic, and when I sync manually heart rate data is available on Garmin Connect for a few hours only...

So daily records lack data (see picture attached).

Any idea why or how to solve this ?

Thanks