On my 08 Jayco Jayflight 23 FB G2 the connection box in the trailer from the factory where the cables hook up to inside the trailer was connected wrong. They had antenna cable hooked up to cable connection and cable connection hooked up to antenna. I found this out by doing what you did. Ran a wire straight from the antenna to the TV and then from the park cable hook up to the tv, I had to change the hook up behind the plate in the trailer.
If you are born once you will die twice
If you are born twice you will die once