When you pick a new colour (for clouds), the colour you are picking has a saturation level based on the initial colour contrast slider bar. When you click "OK" on a new colour, the colour contrast slider bar automatically adjusts, but changes the colour you picked. You have to copy the initial colour contrast and paste it in after changing the colour to get the exact hue you picked.
Haven't tested this with anything else as I'm stepping away for now but it is kinda annoying having a second step to just simply picking a colour. It's especially annoying when copying colours over to another cloud layer, not only remembering the RGB values, but contrast level.