Posted on 01 September 15 at 12:52
I just did this recently, but opposite -- WP achievements to sync with Win 8 -- and that worked fine.
I'm not sure if completing the tutorial was necessary, but once I closed out the program and re-opened it, all of my achievements synced up.
Of course, with the latest update, XBL achievements seem to be down again for this game.
Rollus Tidus