sync prob w proRes files exported from good sync TL

I have Canon h.264 footage (an interview) that needs to be synched up with a wave file. Did it with PluralEyes, looks good. Go to export the resulting new seq as a ProRes Qt and when I reimport the result it looks several frames out of sync (video late). I have a hunch others have run into this before, what to do?

I'm running FCP 7 on a system that is unfamiliar to me, it is equipped with a Kona card. Sync on the reimported ProRes file looks bad on the FCP Viewer and on the video monitor.

Also this is the first time I've had to sync footage in bulk, creating new originals. This is an ancillary question… but I'd like the new sunk-up ProRes files to mirror the Canon originals as much as possible, duration, TC etc. Besides the sync issue, any other work flow tips to achieve this?

Thanks in advance,

Paul