I have a file I'm preparing for print so it is in CMYK. I'm attempting to smooth out an area using the gradient tool. I have very specific CMYK values (C100 M0 Y30 K30). It's a simple gradient, one side is my CMYK colour, the other side is transparent. When I use the gradient tool on my image, the CMYK values change to C100 M27 Y43 K4. I have checked both sides of the gradient colours, even the transparent side, to make sure they both contain my specific CMYK values.
Mode is set to Normal so there is no multiplying or lightening of any kind.
I've done this in the past many times and have never run into this. Not sure if I'm missing something, or if it is a bug.