That's a good point.
I did first suspect the 50A to 30A adapter. My Coach came with two and the first one (when my problem first started a year ago) seemed to be related to the adapter. I tossed that one out and now use the other adapter, but the problem still occurs Maybe I should toss that one too. It looks fine on the outside, but one can't see inside it.
Currently I use a 50A to 30A and a 30A to 20A plugged into that.
Does anyone make a single one-piece adapter for 50A to 20A?