We've recently upgraded to Exchange 2010 from Exchange 2007. Since then, when I create a new Distribution List it does not show up in Outlook. If I connect to OWA it is there. If I force a download via Send/Receive - Download Address Book that still does nothing.
The only way I can get it to download properly is to go to C:\Users\user\AppData\Local\Microsoft\Outlook\Offline Address Books, delete the address book, and reopen Outlook. Clearly I can't do this for 700 users everytime I update the Address Book.