Missing sleeping b.bat and HR in Garmin Connect after sync

Maybe once every couple of weeks, I notice that GC shows zero data history (HR/Stress/BBat) for the sleep period, just a gap from when I went to bed until after I got up.

Checking on the watch, the data is there, it's just missing from GC.

Does this happen to other people?

I'm using an F7Solar, with sleep mode enabled, using power saver etc.