Most people think that dual 50 amp breaker .. .if one trips. both trip.
NOT TRUE. it is not a dual breaker, it is two breakers, both in the same case, with a piece joining the handles.
But each breaker is independent of the other.
One can trip and the other remain "Set"..
Turn them off, press HARD to the off position and then restore (Turn back on) them. See if that works.. Following that is replacement of said dual breaker.
Also... Have seen this in campgrounds. never in an RV. but make sure they are fully SEATED (Push back/in on the top of the breaker)