Final Cut Pro's Digital Cinema Desktop feature may display a blank white image instead of your video, if it is viewed on a display that is connected to a second graphics card.
Final Cut Pro is able to display its content on one or two computer displays, but in order to utilize the Digital Cinema Desktop feature on your secondary display, it will need to be connected to a second port on your main graphics card. Digital Cinema Desktop is not supported on a display that is not connected to your primary graphics card.
302671: "Final Cut Pro supports up to two displays at a time"
This document will be updated as more information becomes available.