Custom post-processing effect: Multi-pass blur possible?

I was trying to create a full-screen blur effect, to blur the screen behind my menus when pausing the game. I thought that with the introduction of custom post-processing this would be simple, but it seems that most gaussian blur filters I see take two passes, one for horizontal and one for vertical. I think they can also be accomplished in one pass, but my understanding is that the performance is pretty bad for a single-pass blur?

Anyway, I tried adding two passes to a custom post-processing shader, but it seems only the first pass is executed. Are multiple passes not supported? Or is there a trick to getting it to work?

I suppose as a fall-back plan, I could add the effect to my volume twice, and have each one process either horizontal or vertical, but that sounds a little silly.

Or, is there a better way to achieve a full-screen blur effect these days under HDRP 7?

I’ve posted few links here Image Blur in HDRP

Thanks. I check it out.