iBooks won't sync my iPhone with my MacBook Air

If I'm reading a book on my iPhone and later want to pick up where I left off on my MacBook, the page doesn't sync up. It used to do this but a setting must have changed somehow. Anyway, both devices are set to sync: iPhone app setting is "Sync bookmarks and note" as well as "sync collections" while my MacBook iBooks Preferences are the same.

Any ideas?

Thanks