Well, how are you viewing this? What external monitor and IO card? The Kona 3 only supports 2K output, and will scale that to 1080 for viewing on an external broadcast monitor. The Kona 3G and Decklink 4K will do 4K, so that leave us with monitoring. There are 4K monitors...are you using one of those?
Grading with Color requires an IO card and external monitor. The Viewer in the Color interface is extremely innaccurate.
I figured it out. At least I believe I did.
r3d Files come with Quicktime wrappers - basically Reference Clips, that are linked to the r3d files. There are 4 wrappers for each file: Full, High, Medium, Proxy. Full in my case would be 4480x1920, which is too large for Color to handle, so it seems to fall back on the High wrapper, which has 2k resolution. I now rendered my sequence to ProRes422HQ with 444 Chroma sampling with REDCINE-X and downscaled to 4k 2:1 so Color can handle it. Works like a charm. Although the color range seems to have shifted, even though I had Gamma Correction set to off.