I found the issue–and yeah, it should’ve been obvious. Peter Macauley answered this a few years back: “Apparently the problem was with the way your FCP sequence was set up and not with the filter. The BCC Deinterlace filter requires that the FCP sequence field dominance be set to *none* in order for it to see both fields, so if you can set the field dominance of the sequence containing the clip that you wish to filter with the BCC Deinterlace to none you should see the result that you were expecting.”
Problem solved.
John Farrell
http://www.farrellmedia.com