I had a similar problem. I had been using Log and transfer for over a year to import Z5 footage off CF cards into Final Cut 6. Then I upgraded to FCP 7 and it just stopped recognizing the cards in the log and transfer window.
After re-installing the Sony plugin though it works fine again.
You can get it at https://support.d-imaging.sony.co.jp/www/pro_hdv/fcp_plugin/
Thanks to the Miraculous Pixels blog for the link.
-Rob