Same issue here. Contacted sony about this shortly after posting and they pointed out the issue with Symantec. Went to Symantec preferences and disabled it and that did the trick. Can re enable when not using the XDCAM drive.
This issue has just surfaced for us. I have been unable to figure out a solution. Seems to work fine if i copy the XDCAM folder to a local volume but cannot link directly to the optical disk. Were you able to find a solution?