Hi,
indeed, there is a small logical glitch in this action, it deos check for the "None" first, but then it runs every update and then doesn't check so unless you exit that state before it runs again it will set the volume to 0.
Can you try the action attached to that post? if that works, I'll put it on the right section and will make a ticket for it to go on the next release.
bye,
Jean