I was shooting a corporate job and the skin tone was always brown no reds etc. I don't know why, I did the white balance on the paper in the light, tried diff angles and always brown face?? IN SD mode.
SD has nothing to do with it, it's probably the WB target you used that is the problem. It might have had a UV treatment applied to it (this is often the case with premium papers, the treatment is intended to make the paper appear "whiter"), or if it was a single sheet, it might have been translucent enough to allow light to penetrate from behind.
You should be able to correct this in post without any trouble.