I'll be curious to see if you get any answers. I had this happen recently with pink too. I made 150 or so little pink fondant (I colored myself from white fondant) flowers to go around the sides of a cake by the time I got done they were all different shades of pink to the lightest being white. I wasn't sure what happened. It was like the color just disappeared in them.
4/22/14 at 6:30am