I have a Challenger 37KT with a AVM111NAVLH navigation unit. I like to use the rear view camera as I drive because I tow a car and like to keep an eye on it. When I use a directional it switches to a side view camera and as the directional is canceled so is the camera monitor so I have to manually put it back on the rear camera.
The manufacturer has put out a firmware update to eliminate this problem on several models. The update and instructions can be found on their website.
Go to https://mito-oem.com/
, click on "Support" on the top bar and then click on "Firmware", select the correct model of your unit. Be sure to follow the directions for the correct sequence of steps.
After this installation your camera will return to rear view after the directional is cancelled.
Good luck and happy travels.