Bizarre fueling situation. Issue #1 on trip.

Sometimes the fuel filler pipe has to be longer and more convoluted to reach from where the chassis manufacturer places the tank, to where the coach manufacturer places the access door to the fill pipe. That's assuming the upfitter doesn't move it, to add some piece of equipment. My 2002 Roadtrek was like that. They moved the tank forward to make room for the Onan genset, and had to run a longer fill pipe with an odd bend in it to reach the access door. It was always hard to fill the tank without rotating the nozzle 90 degrees to the right, to get around the oddball bend in the pipe.
Maybe?
Interesting that sloshing the fuel fixed the problem. Probably not the same issue as my Roadtrek, if that did the trick.