New terrain was generated over where my world should have been, and the size of the world was decrease from 325mb to 140mb. On another note, upon finishing the conversion and launching for the first time, a few seconds after spawning the xbox froze completely and required a hard reboot. I'm torn because this world is now 5 years old, and for the last 8 months (since the december update) I have been unable to launch it. It's been awful, not being able to use my favorite world, so I am really hoping that this new engine corrects whatever went wrong with it.