Black squares appearing in UDIM textures

Hello, I recentrly tried to use a UDIM workflow on an imported mesh from reality capture (a point cloud becoming a whole mesh), I have 60 UV maps to do so, everything works fine only for one part; on the icon of my virtual texture in the content browser, there’s two little black squares, that suddenly are reported on my scene (images below), like squared black patches being around, any ide of where this could come from ? The textures are in 4k resolution btw and virtual texturing + nanite are enabled.
Thanks in advance !

patches on scene :

and VT icon with two squares :
two squares