Thanks
@WAS and
@Dune , putting the image map shaders on either inputs for a Multiply Scalar or Multiply Colour both worked here! Putting it into the Mask Shader (BETA) works just as intended, solved!
Also, it seems both node descriptions are exactly the same:
"Node Description & Purpose:
The Multiply family of nodes allow you to multiply the colour/scalar/vector coming into the Input by the color/scalar/vector coming into Input 2. The multiplication is component-wise, for example with a colour"
Maybe one can be deprecated?