I have already seen the problem. 3DS Max "don't like" long names, so it renames automatically the textures by removing some characters.
Export in Wavefront OBJ and check export textures in a new folder, 3DS Max will assignate (to the MTL) the new names textures.
Export in Wavefront OBJ and check export textures in a new folder, 3DS Max will assignate (to the MTL) the new names textures.