I had the same problem and tried various ways to fix it. Nothing worked… until I changed the editor language to English instead of my native language. After restarting the editor and assembling the MetaHuman again, the correct textures finally appeared and everything started working properly.
I’m not 100% sure if this was a coincidence or a real fix, but if you’re facing the same problem, try switching the UE interface language to English and give it another shot.
Hope this helps someone!