This happened to me on the first trip last year in my 3011ds. The battery would charge with the engine running or the generator but nothing on shore power. It ended up being the converter under the bed. I did some voltage tests that the company who made the converter had on their website and it was definitely bad. I replaced it and has been fine since. We had to run the generator during the day on that first trip and use as little power as we could overnight. The lights would barely work in the morning.
I really hope yours is not that and is just a bad fuse or something. I looked at everything else in the RV before even realizing that I had a converter