Mask with sprite stencil and custom material?

I’m attempting to make a UI mask with a sprite stencil. I have a shader that I’ve made that essentially takes the sprite and adds a glitchy effect to it… (like a static glitch on a hologram display) It works great with sprites and does exactly what I want it to do. It does a great job taking the edges of a sprite and distorting them a little bit in an animated way.

I would like to apply this effect to some spine animations, but have had a very difficult time getting a shader to work on a spine object correctly… so for the time being, I thought I would try creating a mask that uses a sprite stencil… and putting the shader/material on that sprite. In theory, I could use a simple rectangle sprite, then use the custom shader material to distort the edges of that sprite and use that sprite as a mask for the spine object… thus more or less distorting the edges of the spine animation a little (there are reasons why we are not adding this into the spine animation itself.)

Anyway… I cant seem to get the above to work at all… neither on a spine object or on a standard sprite… It’s as if the material being applied to the sprite in the sprite stencil is not being used… The stencil remains a hard edged square and doesn’t distort at all. I was wondering if someone could provide insight to what I may be doing wrong or if anyone has an idea for another way to do this effect, I’d welcome that too!

bumping this in the hopes it gets some eyes…