UE4 - transparency in GPU particles

How can I delete a post? This question is redundant now since I figured it out.

I am trying to make my glass GPU particles more transparent. I have masked out the shape using the blue channel. and also used the same blue channel for opacity. I am now trying to dial down the opacity to make it more transparent.
It doesn’t appear to be working. it stays at 100% opaque. Does anyone know why?