my only remark is that for myself, when I set the sliders too dark, it seems to "default" back to white/gray. I'm not sure what the nature of "too dark" is. It's not like you can't have ANY sliders low, but if ALL the sliders are low then it breaks. Maybe it's something about the average of all the sliders, or maybe it's something about the value of the highest slider. Wouldn't be that hard to test, I guess.
anyway that's probably not your problem, if you tried multiple colors and not just spooky dark ones. I think i saw a text file somewhere in the files that stores the RGB settings as three rows of numbers, so maybe you could see if there's something glaringly wrong with yours, like some reason why it can't be accessed.