I have a loaner 8310 that is running 4.2.2.163 and when i restore it with a file created from a device that was running 4.5.0.55 it won't load the phonebook.
Happened to a friend of mine. Spent hours trying to find a solution. In the end I had her upgrade her OS again. If you are on a BES it should sync when you activate, otherwise, you are SOL as far as I know.