Are you sure it has worked in the past? I posted on one of the undocumented changes threads, how now after a recent patch, the game saves your colour picker coordinates for the car colour. However, this feature has only been available for decals to my knowledge, for when changing a decals default colour using the colour picker, which also changes a multi coloured decal into just the one colour that you pick. Leaving the livery editor mode and coming back always erases that memory. It probably has something to do with the fact that some decals are made up of numerous colours, as they are shapes rather than just a simple pallete swap that covers a fixed area of the car when just simply painting the car. Is a pain though, when all you want to do is continue something as simple as a stripe in the same colour as the one you did before. In that respect I always screenshot my colour coordinates.