After using ISM during the night, I've noticed that heart rate glance doesn't show my overnight heart rate at all. Pulse OX time series is missing as well. The missing data is present in Garmin Connect app on my phone.
At the same time, things like HRV, sleep score, body battery seems to be in sync.
Garmin Connect android app: 5.21
Watch: Epix Gen 2 - SW version 25.11
ISM firmware is 3.82