The sheen textures are not displaying properly when loading in a GLB with the sheen extension. The bug seems to of been introduced around 5.11.0. It worked in some of the earlier versions of 5.0 that we’ve been using, but broke once we updated to 5.13.0.
If you use the inspector to toggle some of the sheen options, it seems to fix it, until the toggle is set again, and then it is broken again and changing the toggle again has no effect. Very strange…