Roger,
What you are seeing is absolutely a symptom of a bad connection at the pedestal. Do you carry a meter? If not, you should. Get a juice friendly acquaintance to walk you though what to do with it.
The reason everything worked with the 30amp adapter in there is that all of your equipment is good.
Tomorrow, go out there again and flip the 50 amp breaker on and off a couple of times and try it again. If the condition persists (only one side works) then tell the campground that the breaker has failed and should be replaced. If things work this time, tell the campground that the breaker is failing and should be replaced. (They won't until it doesn't work at all.)
Good Luck Roger
Matt