Yeah, I tried that a few times to no avail. From your post I thought you meant there was another setting beyond easy set up.
However, I did resolve the issue. Or rather, found a work around.
It seems that there was some break in timecode when I made sub-clips in XDCAM Transfer. So, the first subclip was fine, then the second clip was off a little, third even more, etc etc. The work around I figured is to import the master clip into FCP then make subclips there, as opposed to during the import with XDCAM.
I’m not sure why this would happen, especially since the sub-clips play fine in Quicktime and iMovie, but for some reason FCP doesn’t seem to like XDCAM subclips.