For some reason I cannot post it in beta section, please move it to where appropriate.
My OHR readings yesterday showed the same pattern, as before:
Indoor track, first km was fast (~4:50), OHR is for sure too low. Just made 2k warm up before that.
Please consider it in your further upgrades.
Warm up:
https://connect.garmin.com/modern/activity/17709506347?share_unique_id=56
Main run:
https://connect.garmin.com/modern/activity/17709737753?share_unique_id=53
In case you need it - any permission necessary you can have.