Hi there, just was going back through to update default pictures for new materials and the new site design (I've been away for a while) and noticed I can't set a picture that contains multiple materials as the default for a model. Surely this is not intended functionality?
Currently the material you set as the default material, will be the default image. I'm assuming the parts are different files? Set the image to be the material that file associates with. I know not exactly what you're looking for but should give you the intended results.