It was the Visualization Extensions. But as noted in your attached discussions, the story I was trying to export was not leveraging any of the visualization extensions. It was the simple fact that I had installed visualization extensions that was causing the problem. After removing those extensions, I was able to export to PDF successfully. (NOTE: Data Extensions don't seem to have any impact.)
This is a real bummer... hope SAP has plans to fix this bug soon.
Thanks,
Josh