Strand based hair Cutout Opacity Mask

quindor

Hi!
 

does someone know how cutout opacity masks work with SBH? It doesn't seem to mask out parts of the hair, it just makes the hair kind of thinner. I tried to disable limits and make the cutout opacity value really high, but it didn't do anthing.
I made two quick renders - One has the mask texture applied as color, so in my understanding it should mask out the black parts.
The other one is the actual result when I apply the mask as cutout opacity.

 

Does someone know how to get this work?

 

thank you!