I'm having almost same issues with a MBP mid-2012 (no retina) core i7 and 8GB ram.
In my case it looks like some problems not only on export, it happens too trying to render any part of the project.
It looks like some changes of the 10.0.6 regarding the rendering (maybe some incompatibility with the nvidia gt650M of your and my machine.
Anyone using mid-2012 MBP machines with problems like this (rendering and export mostly).
I disabled background render to try to edit something, but when I try to render it start to hang.