I tried to repaint the background of the cycle in the editors.
Now NOTHING happens. Kaputt!
It used to work very poorly, then it got worse … now nothing happens.
As time goes by the controls are fewer and … c’mon???
I’ve never seen a program at the sophistication level of Cubase have issues with this.
What’s the problem with getting the color schemes right in Cubase? 
Everything is entangled in everything else and if we change one value then values on another page get screwed up.
And you can’t go back and edit because everything is gone if you change the colors on the Color Scheme’s page-
to reproduce
Open the drum editor or any of those editors so you see the Cycle.
Open Menu > Edit > Preferences > User Interface > Custom Colors and find the Editor Area Background.
Change the Cycle region color and hit apply.
Nothing happens.
Why?