What is iCorrect? Some kind of camera profiling tool?
Any time you assign a larger-gamut color space to an image, the color variation between one RGB value and the next is increased, so any unevenness in color gradients will become more pronounced. With color spaces equivalent to Adobe RGB or larger, it is difficult to avoid some posterization/banding because the color intervals between one RGB value and the next are sometimes greater than the eye's ability to distinguish one color from another.