Versa 2: always shows heart rate but doesn’t track sleep

[EvcallTX]

Versa 2, update 71.6.19, always shows my heart rate and the graph is uninterrupted, but my sleep tracker tells me I only get 1.5-3 hours per night or will stop tracking sleep then start again hours later.  One night out of 22 I did get tracking for over 7 hours of sleep, but only once.  I have refreshed, updated, rebooted, factory reset, checked all the settings that have been suggested. I have positioned it perfectly on my non-dominant wrist, and also moved it up a little and down a little.  I have tightened the strap one night, next night loosened the strap.  It is fully charged.  I tried it on dominant wrist.  I have used Bluetooth and WiFi.  I have no tattoos or scars on my wrist.  My wrist and the Fitbit are dry, the sensor area was wiped clean.
why will it track my heart rate but not my sleep!?!?  

[Rich_Laue]

Heart rate is not the only data collected to detect sleep. You can turn heart rate turned off and simple sleep should still be recorded.