This one is interesting. An actual friend of my non-rv’ing friend has a water pump issue he asked me about. His water pump works fine while on generator but only the pump doesn’t work while on shore power. His 12v lights work, slides work.. He has no meter to test anything of course and he’s over 100 miles away, quite the drive. Wonderful. The converter sounds like it’s working properly since the lights and slides work, the 10a fuse to the pump sounds fine since the pump works on the generator. The pump diaphragm and check valve work.. Maybe lower voltage coming off the shore supply? I’m still trying to research it to help him out.