TT keeps popping shore breaker

Now that I think more about it, I recall that we did have a similar issue with the TC years ago that resolved for no real reason. I talked to either Parallax or Northern Lite about it and am now remembering that they said a GFCI outlet may not work with a converter as they sometimes have unbalanced hot/neutral. I don't recall why but I'm guessing this might be the issue. I'll try moving to a different 15A plug to confirm.

I have the TT in a metal building but there is no power run to it. I have intended to run a 50A out there but haven't gotten to it. If this continues to be an issue, I may have to do something.