Btw, you have both RN and SM and they cancel each other because they are "inverting" each other (0% smoothness = matte surface, 0% roughness = shiny surface) Choose just one. I suggest keep RN it is the most rough surface if you want that.
(replying to the first post)
Maybe it could do something with the mesh itself. I do not know. This is beyond me. I hope you will get helped. Maybe if you want you could upload the blender file including the textures files in a zip file here to forums and someone can take a peek.
EDIT:
Adding again, once I had problems with something not working, then out of frustration I selected the object in Blender and hit ctrl+C to copy it, start a fresh new empty file, pasted it into there and lo and behold it worked.