Hi Brian, sorry I can't help here other than replying to bring it to the top again... no syncing here at all, not even a TV, much less an Apple TV!
Oh wait, might try this...
To find out if it's system wide or user specific, try this...
Open System Preferences>Users & Groups, unlock the lock, click on the little plus icon, make a new admin account, log out & into the new account.
Does it work in the new account?