There seems to be a problem on Amazon’s CreateSpace platform. They’re looking into it now. Basically, files that have been uploaded and approved were rejected when other files were re-uploaded and this became a repeating pattern. Upload a bookcover, it’s approved but the internal file needs something tweaked. Upload a new internal file, and the cover that was fine before is rejected.
I’m in communication with them and it should all get worked out in a day or two. My files are fine. When I sent them a download of the approved internal file that was subsequently rejected, they realized they had a problem.