Same here, 2014 Chevy Popular 190. What I eventually found out is Roadtrek replaced the factory high mount brake light with a cheap aftermarket unit with a camera. It was poorly made, not properly weather sealed, and completely corroded inside. Neither the camera nor the brake lights worked when I acquired my 4-year-old unit. I searched online ("Chevy Express center brake light with camera") and found an identical replacement (no, thanks!) and some other possibilities. It was really hard to tell looking at pictures whether they were any better sealed than the junk supplied by Roadtrek.
In the end I got a plain old factory high mount brake light from Chevy (well sealed).
The video line is still there if I ever change my mind. Personally I'm not a fan of rear view cameras. They make one more thing to look at and mentally integrate, and we often have a trailer attached anyway. The side mirrors are excellent (love the lower wide angle section so you can see the tires and any curbs). I can back the trailer and have even parallel parked the van without the camera.
Maybe someone else will be along with a specific high quality replacement recommendation.
2014 Roadtrek 190 Popular
2008 Scamp 13