You need to download and install the Sony SxS UDF Driver, available here http://pro.sony.com/bbsc/ssr/cat-recmedia/resource.downloads.bbsccms-assets-mkt-recmedia-downloads-upgrades.shtml
This issue is now resolved. The Panasonic P2 driver included with Qio software version 1.2.3 and later is 64-bit compatible. Installing Qio 1.3.2 or later adds P2 support to systems running OS X in 64-bit mode, including Mavericks (10.9) and Yosemite (10.10)