The OP moved on and this is an old thread but I have the same question and the solution isn’t working for me.
It creates a horizontal line accross the lower third of the screen. Everyone below gets the post processs effect and everything above doesn’t
I’m also working on an outline PP material and also want to use a stencil value to exclude certain actors. In my case, the actors I want to exclude are foliage actors that used “masked” materials, and I wonder if that could be part of the problem?
I’ve tried plugging in that bit of code in several places with same results.