Just to follow up on this. We tested this yesterday on our AppRiver Hosted Exchange server (2010) environment, and it worked fine. All contacts sync'd down to the Outlook 2011 for mac.
So, I have narrowed down its not an issue with the client (outlook 2011), its not an issue with the contacts (.pst), it's not local side so it has to be server side.
Why does it work on Exchange 2010 and not Exchange 2013? Or is it just something now set right on O365?
Any Help would be appreciated.
Thanks