MBR vs GPT never made any difference for me...on 39.7 got the gray x pretty quickly.
Now I've got a different issue on 42.3-
Plugged directly into a front USB port it has worked without issue for 3 days now.
But initially I had it plugged into a USB 4 port hub (that was plugged into a front slot). Also in the hub where the 2 phone charging cables in the front dock.
When I plugged they key into the hub the camera icon appeared, red dot, working fine it seemed.
Next time I started the car- no camera icon. Removing the key and plugging back into the hub and the icon came back- red dot, appears to be working fine.
Next time I start the car same thing.
So it WORKS plugged into the hub... but seems to forget it's there between car starts unless I remove/replug the key.