Still the same bug since, I guess long…
If you set channels to either left or right zone in the visibility inspector for the mixer once you can
a) not scroll through the channels on the right/left zone to at least get access to those outside the visibile area
b) you can never move the whole channel set left or right to decide where to focus on: left, mid or right.
c) you will even not see the middle zone anymore in the whole mixer
That makes the mixer zones rather useless already in middle size projects.