It looks like you have physical sun and sky for this, which may add an additional gamma correction of 2.2 for your camera via an mia_exposure_simple node, I think. Checking in Maya 2016.5, it doesn't appear to do that anymore, but that could be my setup. So I believe with color management on, you would get double the correction, which you don't want. Either disconnect the exposure node from your camera, or turn the gamma correction to 1. I hope that's the solution.