Ok, so I need some help with a 1x13 setup on my LCR018 frame...

Context: I was using a SRAM 1x12 cassette without any problems with a Wheeltop GeX groupset. A short while ago, I decided to upgrade to 1x13, so, taking advantage of the GeX ability to adapt to different cassettes, I got a SRAM Rival XPLR 10-46 13 speed cassette and compatible flattop chain. Changed the cassette on the wheelset, adjusted derailleur limiting screws, went to the Wheeltop app, set the derailleur to 13 speeds (instead of the 12 it was on) and started adjusting/reindexing the gears. From the 46 tooth cog to the 11 tooth I have 12 speeds running smoothly, perfetly indexed, but I couldn't get it to shift to the lowest 10 tooth cog. Initialy I though it was just bad adjustment of the lower limiting screw on the derailleur, but after some fidling, I still wouldn't shift the lower, or, it would, but only for a fraction of a second, going up again to the 11 tooth cog. That was when I started to notice that the UDH piece had some scruff marks on it's inner side, facing the cassette. It was then clear to me that the chain was rubbing against the inner face of the UDH, in 2 spots, relative to the axle, on the upper and bottom parts. At first I thought this must be due to some problem with the rear hub/freehub body, but I already tried other 2 rear wheels from different wheelsets (3 in total) and the problem remains. It seemed to me there was simply no space/enough gap between the included UDH and the limit of the cassette for the chain to clear and run on the 10 tooth cog. Has I have an extra regular UDH laying around (not this ultra-light version that LC ships with the frame), I took the original out and tried that one, and it only got worse, as with the normal UDH it seems I have even less gap between the UDH inner face and the cassette, like 1mm less!

So, I seems to me it's not a rear hub/freehub problem, nor a UDH problem, so what, is it the frame?!?

I attached some pictures below to show the problem I'm describing.
I guess some of you here are running 1x13 speed cassettes on this frame, so this should be possible for me too!
Please share your thoughts and ideias, I'd appreciate some help!
Many thanks.