I see this problem in couple scenes that I tested, there are either textures on characters not updated or whole parts of characters are simpyl not displayed at all. Rendering with XPU shows them all there and working but no luck in view port. yes I turned on off lights texture display.. no luck.
I have this on cachyos and fedora Linux, haven't tested in windows yet..
Selected all of the character in scene graph:

Ok figured it out.
MtlX PBR Texture set node is not working. When I remove it and use MtlX Image node then it is fine.
That is in Houdini 21.0.440