Also same problem, doesn’t seem like it would be a big deal but I think I’ve found the issue is related to Translucent materials not being recommended for mobile.
I created a new project not targeting mobile and added my same fbx and materials to it, it worked fine.
I’m not sure the exact project setting stopping it from working because according to the documentation while it isn’t recommended to use translucent materials it states they’re just not performant, which is not what we’re seeing.