An object in a .blend file that is imported to Sketchfab does not show material, just that white "look."

I have imported many .blend files into Sketchfab with no issues. But I am stumped on this issue and can use help, please! =)

I have an object (treasure chest) that is part of a scene. The chest looks fine in the Blender Viewport but when imported into Sketchfab, the object has that white look like when viewed in the Blender solid display mode. Again, it looks fine when viewed in the Blender Material Preview mode. Only this one object has this display characteristic in Sketchfab.

I even copied the object and pasted into a new Blender model . Looks fine. But , again, in Sketchfab no material shows only the white “look.”

Something about this one object is wonky.

Looking forward to being “schooled” on this one.


How is the material defined? Sketchfab only has limited support for shader nodes, and no support for procedural materials.