Looks like it was a change for 2021, I have the 360 cameras on my 2020 (Ultimate trailer tow) and I can't use any of the cameras in motion.
Hopefully there will be a way to update the software in the 2020's to make it work but not holding my breath.
This is the excerpt from the 2021 manual:
Camera Views
The camera button is located on the instrument panel. Pressing the camera button activates the system.
When in park (P), neutral (N) or drive (D), only images from the front cameras are displayed. Press the camera button to display the front camera image on the display screen.
When in drive (D) at speeds greater than 6 mph (10 km/h), properly equipped vehicles can access two camera views. By pressing the camera button on the instrument panel, the rear high view camera and auxiliary camera can be viewed.
When in reverse (R), only images from the rear cameras are displayed. When you shift into reverse (R), the rear view camera image automatically shows on the display screen.