Forerunner 265 no stable reading and stopping app on watch

[Sprk-nl]

I have followed the installation instructions from https://docs.sleep.urbandroid.org/devices/garmin.html
The first few minutes SAA receives movement of the watch.
heart rate is missing sometimes, while movement is received each 10 seconds.
After a few minutes the measurement of movement and heart rate stops completely in SAA.
When I check the watch, the sleep app is not active anymore.

Phone: Samsung Galaxy S22
The apps SAA and Garmin Connect are allowed to work in background / no energy management is active.

Watch: Forerunner 265
sleep mode = on
do-not-disturb mode = on
De app is not mentioned on the website as supported device, but is mentioned as fr265 in the manifest.xml

I've used the SAA for years with a Miband 5 and 6 before.
Only now when switching to this Garmin, it's not working as expected.