Currently, when you view the mask in one of the EFEX modules, it shows the mask being generated as white, regardless if it is a control point/line mask or a negative control point mask.
It would be easier to see what is going on if it would display the mask as white for positive control point, black to show the negative control point, and shades of grey if the opacity of the filter is other than 0/100%. Hope this makes sense
Only if you click on the mask symbol in the local selections will the selected area of a negative control point etc. also be displayed in white. However, if you click on the effect mask (square consisting of a black and white triangle) at the top right of the filter, only the areas to which the filter is actually applied are displayed in light color.