I have a piece of footage rendered out from AE that is 3276x720 ProRes. It will import fine into FCP and display in the sequence timeline and canvas with no problems, but when I go to render it for preview, it throw a codec error. Is there a width limitation for footage brought into FCP? Anything else going on here that stands out.
FCP 7 and earlier was designed to work with broadcast formats...frame sizes and frame rates. So 720x480, 720x486, 1280x720, 1920x1080. 2K is 2048x1556. 4K is 4096x3112...although FCP has issues with that format.
Not sure what format your video files are...3K? And it looks like a banner, or video wall kind of format. That's best dealt with in Premiere Pro.