I'm not 100% sure but I'm pretty sure I was able to do this before with BES 3.6 but I could be wrong. A lot of my appointments are recurring i.e. Birthdays so if I don't see them I'll forget about them. I'd hate to have to put reminders on them just so they would sync.
UPDATE: I decided to try and switch from wireless to sync to wired and it put all my appointments back in. Then from the unit I asked for it to do the wireless synce from the handset and for some reason it seems to be staying on the unit. So it could be a just a matter of just re-reconciling (if that's a word)