After clicking the 8 and making the change, are you saving the theme?
Because all the other lit areas change immediately when you click and change them. The power switch will not change until you have saved the theme.
Ok on the 15 R4 this doesn't work. I tried to change it by clicking the 8, making changes to the color, and then saving the theme. Unfortunately, nothing happens. It stays exactly the same. This means that the actual settings are not being updated. It's also possible that it's a bug in the firmware for the lighting control chip.
I actually had the 17 R4 before I got the 15 R4, and the 17 didn't have any of these issues. The command center worked a lot better on the previous gen. Dell has improved a lot and I think their support is very good now. But as a programmer, I am very disappointed when they release software like this. I wish I had the source code so I could fix it myself.