I had exactly that problem with my RV , though a completely different make. The metal filler as was at at an incorrect angle. The filler assembly,in my rig, was connected to a rubber hose , which was connected to a metal pipe that ran to the gas tank. This "coupler hose" was slightly too long, resulting in the gas filler assembly to mounted to the rear RV body at an incorrect angle. It was an easy thing to correct by measuring and reducing the length of the rubber hose.
I can't says if yours is set up in a similar way, but your dealer should correct this, what ever the cause, under warranty.