Fixed Volume Command not working

The Volume up/down command is working fine...but when I try to set it to a fixed value it doesn't change the level

For Example,
AV|4~Volume~45 (doesn't do anything except flash up the current volume on the screen)

AV|4~Volume~up (works fine)

Thanks!

What receiver are you using? This works on my Denons though I don't use it because it operates via absolute values and i prefer the relative scale.

It's for the eARC connect soundbar (Sonos Ultra). Up/Down works fine...setting it to a fixed value doesn't work. I use the fixed value for my Anthem AVR, and that works great. I have a button "Movie Level", "Quiet Level", etc. and use them as quick access buttons.