GF doesn’t use layers, it uses colors to differentiate operations. This is covered in several tutorials you can find with the search function. Make your different operations different colors and it should turn out as you want.
Also, you will need a vector for your cut and score. Rasters can only be engraved.
The suggestions above are pointing you in the right direction. You get one separate operation per color.
So duplicate the cut line (right on top of the first one) and give the copy on top a different stroke color. That way you will get a separate Cut operation for it that you can convert to a Score. (Just on that one path.)