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Just upgraded to the latest security release of Mavericks..

10.9.2

And now I'm not able to airplay extend my desktop. I have a second monitor connected and the third by AppleTV. Since the upgrade I just get a blank screen. Audio is being sent however.

When I try from my laptop also running the same update it's working, but then it's as the second display rather than third.
 
Working for me on 1080p Apple TV and early 2013 15" rMBP. Running 10.9.2 and latest version of ATV OS.
 
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