Framerate hardcapped at 30fps?

I am testing an AIR 32 application in the debugger on Windows. This is a Stage3D/Starling app.

I set the application framerate in the document class:

stage.frameRate = 60;

However, using the Starling stats window, I can see that the application is only running at 30fps. If I set the framerate to 10, the application does run at 10fps, but anything higher than 30 and it caps at 30fps.

I used to be able to run apps at 60fps in the debugger. Is this a bug, or did Adobe change the specifications?