DEF cap won't screw on - Causing? and who sells DEF fuel caps?

I have a 2020 Peterbilt and today I fueled up and the DEF cap came off fine. After filling the DEF I went to put the DEF fuel cap back on and the stupid thing will only screw on halfway. For whatever reason it seems only one side of the two seperate perpendicular hooks underneath the cap (if that makes sense) will actually screw into place, while the other side won't slide in like it should.

Thus, leaving my DEF fuel cap only halfway screwed on instead of fully.

I checked the rubber piece around the DEF cap to make sure it's not in the way. It seems fine. I don't see any obvious bends or cracks on the two perpendicular pieces underneath the fuel cap either. So I don't know what could be causing this?

As of right now the cap is screwed halfway secure, so no DEF should leak out as the cap won't move around that much. And luckily I'm down south for now so while the temps will dip below freezing during the nighttime tonight and tomorrow, they won't be below 0 or anything extremely cold so I'm thinking the DEF fuel shouldn't freeze on my during a 10 hour break.

That said, has anybody had this happen to them before? What could be causing this?

I checked the TA and Pilot tonight but neither one carry spare DEF fuel caps, as I was thinking I would purchase one of those and if that didn't screw on then it's got to be something bent on the actual DEF hole itself, right?

But neither Pilot nor the TA sell them, they only sell regular fuel caps but not the DEF fuel caps.

Is Peterbilt/other similar model truck shops the only places that will sell DEF fuel caps and stupid question, but are all DEF fuel caps universal in size for semi trucks or do different brands have slightly different measurements for the caps? And what could be causing this do you guys think?

Any help would be appreciated. The truck has 250k on it so it does have some wear and tear, though this is the first time I've ever had a problem with a fuel cap before.