It's been over an hour laying down with resting HR of mid 60s yet vivosport doesn't update the old value of 81bpm which recorded after my walk from 5 hours ago... So
Garmin Connect™ Mobile App
Connect not saving data? : r/Garmin
Garmin vivosport™ (Slate - Small/Medium) Waterproof GPS activity tracker with built-in heart rate monitor at Crutchfield