UDIM tiles not importing properly image texture shader

The issue was partly from the creators side, and partly how Blender manages UDIM tiles, which is clearly still in its early days. It was required to go to these steps:

• Make sure Blender project is saved
• Go to UV Editor
• Hit N for side panel
• Where it says Image>Source, change "single image" to UDIM tile.
• Click the "plus" sign for create new image for as many UDIM tiles as you have - in my case it was 4. You should have in your list 1001, 1002, 1003, 1004 etc.
• The UDIMs will now appear correctly.

HOWEVER:

You ALSO need to do this for all the other textures. So if you have only 1 UDIM tile (which is much more likely) but the normals, roughness, metallic textures are all not importing, you need may need to do this. And of course if you ahve more than one tile, then you need to add to the UV editor as many tiles as you have.

After that, it all works perfectly, and you only need the one Material for all of your meshes for that model. I hope this helps someone.

It turns out it was an issue from the creator's end. I will post more details about what went wrong when I find out, in case this happens to anyone else.