Heyas… I know this is a super-old thread… but I just came across this problem… and as the last response said, its not as big a deal as it seems.
Fortunately I found that the only reason I couldn’t render it was because it was a JPG. When I saved the image from Photoshop as TIFF instead – all was resolved.
I also found that FCP changes the colour to RGB if its CMYK, so copy and paste image into a new file that is RGB, and you get to keep your colours the way they are. Hooray.
Cheers,
Brioni