As learned on Dojo in the past, I am using for good switch between the Mixed and Black Theme: Shapes Filled with Black + Transparency and Options on Page Level : EnableZoom|HoverType=Geometry|#000000=ThemeForeground|#FF0000=ThemeAccentColor|#FFFFFF=ThemeBackground
As this is applied Red color is displayed blue.
But what if I want the RED to stay RED ? What options do I have ?
In that case I apply a small trick. Red = RGB(255, 0, 0). To a shape that I want to show as red, I apply a color RGB(254, 0, 0). That's not fully red, but for a human eye you won't see the difference and DataMiner will not convert it to blue.
Another option, besides the solution of Jochen, is to change the option on page level. As you might understand, you have configured that all shapes with a red color should get the theme accent color. Simply change this to the color suggested by Jochen and you are good to go for all shapes.