Tried that and it didn't work. I set Customized Scene to 4 and Day/Night still shows 2.A weird quirk is if you want to make any changes, go back to customized scene and make your changes and then go back to day/night.
I tried this work-around to change Day/Night mode to Color. I first Selected "Customized Scene" working mode and Profile as "Night". Changing Day/Night to "Color" and saving seems to be persisting these settings. When I change the working mode to "Day/Night Switch" and check, I can see the Day/Night mode is Color in Night Profile. But as soon as I move away from "Camera" screen to other screen like "Live" or "AI" and come back, The Day/Night Modes are changed back to "Auto" and greyed out in both Day and Night profiles.A weird quirk is if you want to make any changes, go back to customized scene and make your changes and then go back to day/night.