Model with UDIMs and Virtual Texture

UE 4.23 now supports models with UDIM textures, so I wanted to test it out, but I can’t figure out how to do it right. My model is mapped wrong.

I’ve imported the “1001” texture into editor, it imported sucesfully all texures into one virtual texture.

Then I imported the model, but when applying the material, most parts of the texture is mapped on wrong part of the mesh. The material is the simplest possible - just the texture wired to base color.

When I diplay UVs in model preview window, it looks like they were imported correctly but only the first UV tile is shown white, the rest is red. Not sure if it means something.

What I’m doing wrong? Do I need to change anything in model, material ot texture?
Is it even possible to combine UDIMs and Virtual Texture? Thanks.

OK, so after some further experimenting, it looks like there’s nothing wrong with my model and it’s a bug in UE.
Problem is that UE creates the joined virtual texture from individual textures wrong. Here’s screenshot from Rizom UV, where the UVs was created compared with virtual texture from UE.

As you can see, instead of starting building the VT from bottom left corner and building the texture right and up, UE started in upper left corner and continued right and down. So workaround right now could be not to use V tiles and instead map all tiles to one U row (so in this case 16x1 instead of 4x4 (well actually 10x1, because you can’t get over 10 in one U row)), but for some reason that does not work too, because VT is packed wrong then. It just repeats tiles 1001 and 1002 multiple times. There is already a bug report UE-80474 for that.