I hate to ask the obvious question, and forgive me, but did you EVER have the signal to the rear?
Our new coach does not have the rear TV wired to the satellite although the wiring diagrams indicate coax was run. Instead that TV is wired to the outside antenna and the three others to the satellite. Go figure.
Then, there's the question of whether you have two receivers. If not, there would have to be a splitter somewhere, I think, to give you two outputs from the satellite feed. That's the way my previous Winegard dome was and that's an easy source of a problem.