I had pretty much the same experience except for one difference.
About a month ago I installed a backup camera and activated it using a rented AutoEnginuity (AE) tool. I had set 5 settings with the AE tool. The camera worked properly with dynamic (active) grid lines BUT no icon on the CONTROL screen (see first photo).
With the release of the OBDLink MX and the Alpha OBD Program (and reading this thread) I got both of them. I checked the settings in the Alpha program and found a setting that was not listed in the AE menus. It was "TRAILER HITCH CAMERA". I marked that "SET" and got the backup camera icon on the CONTROL screen (see second photo)
Yesterday I installed the OEM CARGO CAMERA (using a custom harness by M2Mods-EXCELLENT!) and used the Alpha program to activate it. The Cargo camera now functions perfectly and now have the CARGO CAMERA icon on the CONTROL screen (see third photo).
Functionality wise, if I go to the CONTROL screen I can turn on either camera and that camera shows up with 2 small icons in the top left corner of the screen ( see photo 4). I can toggle between the 2 cameras using the 2 small icons in the left corner.
I did have one misstep, when I activated the CARGO camera I forgot to change the setting "LED CHMSL LAMP PRESENT" and of course got the "Brake Light Out" message on the EVIC. So I had to erase the DTC message. I did this by marking SET the "REAR LIGHTING DTC DISABLE" because:
"In order to prevent cluster fault messages and DTCs related to rear lighting, bulb out detection
can be disabled. For 2015 and later models, disabling bulb out detection will also eliminate any existing DTCs
and cluster fault messages that may have already occurred " (RAM UPFITTERS GUIDE)
So the Rear Lighting DTC Disable worked perfectly and cleared the DTC brake lamp out message. I then went back in and then UNSET the "Rear Lighting DTC Disable" (in other words back to the stock setting condition). Then set "LED CHMSL LAMP PRESENT" and now no lamp out message.
452868[/ATTACH]']
452870[/ATTACH]']
452872[/ATTACH]']
452874[/ATTACH]']