Few days ago I found user:Igor Petrov's post
(No third party watch-face or data-field. Turn off touch screen/backlight/spO2)
I tried a lot and find this.
When opening iPhone's Garmin Connect app to change 955's settings.
Guess what? The 955 will automatically connect Stryd with bluetooth
and estimate use time from "15D" immediately down to "13H".
I guess bluetooth/wifi chips have hardware problem.
Garmin's team may realize this crap but a hardware bug cannot fix by firmware update easily.\
SO THEY JUST PRETEND NOTHING HAPPENS.