Works well here!
What is your amp gain?
Sorry for the delay. Too much work.
I did some tests today and it turns out that the compressor after the fuzz is the problem. Without a compressor after the fuzz the fuzz volume settings perform as expected. With a compressor after the fuzz the fuzz volume settings below zero have no audible effect. I added my Rig as a attachment.
Morgan AC20 FX - 2021-05-20 11-59-30.krig.zip
But even if that's the nature of a compressor to amplify low level signals it should have some audible effect. Right?