I noticed this offline dynasty is from XBox. Did you do anything different before opening it in the editor?
I quickly tried to open an existing dynasty (8+ seasons, with 12 TeamBuilder teams) from my PS3, and I got error messages. When I get a little more time, I'm going to create a new dynasty with 1 TeamBuilder team and see what happens.
It's very promising what you've been able to uncover. Great work!