Forgot to mention that the images look identical onscreen (in the IPR and MPlay windows). It's only when they are saved to disk that the images saved from the IPR seems to get shifted.

I've cleared the LUT and OCIO settings out of the Edit > Color Settings menu. Is there another setting I'm missing?

The new beta release is much improved in its color management. The renders from Mplay and written to disk are a much closer match to what is seen and saved out of the IPR. But there's still a discrepancy.

You can see in the screenshot below the IPR renders come out slightly more saturated. For what ...