We had a similar issue once, we lost power to half the camper. Everything worked on the generator. We assumed someone had messed with the cable the first time. We unplugged, re-plugged and it fixed itself. Then a while later the power issue came back. We checked everything, including the transfer switch and it seemed fine. (Which was quite the process because we had to pull the fridge and everything put of the basement in that area.
We went through this entire process, including blaming the campground pedestal.
Turned out the plug on the camper was loose. We disconnected all power, reseated the connections in the plug and it has worked since. I think it ended up that one of the wires wasn't stripped far enough back to make a proper connection, or, it had a screw loose. (Maybe it's just me with the loose screw!
) I hope I explained that properly.
I'll have hubby answer when he gets a chance. If you need clarification. (I thought I had posted on here about it but I can't find the thread. Oh well.) If you find nothing at the transfer switch you should check there.