The respone of the DxO employee in the link of the thread owner states:
When you import the RAW file into PhotoLab
– PhotoLab will apply demosaicking and convert the RGB values from the “native color space of the camera” into AdobeRGB.
– PhotoLab will apply any color adjustments (saturation, HSL, but also FilmPack color rendering if you happen to use that, etc.) in that color space. I call this “working color space” because it is the color space PhotoLab does most of its work in.
So, for me, it sounds, that all colors outside of Adobe RGB are clipped with or shortly after demosaicing. All color adjustments in ‘Customize’ are calculated inside the Adobe RGB triangle afterwards. So there are no virtual colors, that are moved on demand into the working color space, if you for example change a red gradient into a green one with HSL adjustments.
Clipped does not mean empty spaces, but rather that a color is used instead of the actual raw color, that lies on the Adobe RGB border.