In the last few days I have thought again about the comment of 'Dooley':
@DexLoomer I am curious why you are using this shader instead of the standard mtl_specBump shader. On solid objects like boxes, it does not really serve its purpose.
So, the mtl_specBump does include a specular map, but it is in the alpha channel of the color map.
I asked for a code from 'txesmi' for a shader combination of NomalMap and SpecularMap, because for me the 3DGS standard mtl_secBump shader does not show the SpecularMap.
To test this again, I created a file with normalMap and specularMap (..and put it online as a link) with the same result:Link
NormalMap works, but no SpecularMap is visible!
Maybe someone can tell me why the SpecularMap is not displayed?