Hi David again,
We have reproduced the problem with the null reference and also the reason for that exception. The difference was that in order to reproduce your previous problem we used custom image cell that was always returning an image from the resources as formatted value, while you construct your image manually. The Pdf library we use has problems with manually created images and we had to use different method in order to "workaround" that behavior.
You can download the fixed version from here.
David try to export to Pdf using this new version and if the problem is fixed please tell us so we can populate the fix also to Excel, Html and Print.
Thank You very much for your cooperation.
Sincerely yours,
Support Team