ApproachCircle:
is not a valid skin.ini option, and I don't think it has ever been.
Colors are applied to the approachcircle.png
multiplicatively from the Combo#:
options in the [Colours]
section. Meaning the brighter the color on the png, the more of it will apply.
If your approachcircle appears to be black in-game, that means the png itself is black and you need to recolor it to be white in some image editing software. (or just use a different png / delete it from the folder, which will make the game load the default approachcircle.png)