Final render won't play in vegas 12 latest build
 

I am working on a project that has 3 screens that are 3 projects that are synced.
The 2 outer screens are 1080p and render out fine no problems. The center screen and project size is 3240 by 1080
The main concept render finishes and will play in various players but in vegas it is one green clip.
The sony avc codec won't even start the render. I have tried a .png sequence and when it finishes I get one clip in the folder instead of the 3500 that should be there. Have I reached a limit of vegas?