I manage over 100 blackberry users, most BB 8310's. One of my users has a complicated Address Book on Outlook (800+ contacts, 10+ folders).
I sync'd the BB to the server, all 800+ contacts showed up in their respective folders. A day or rather hours later approx 250 contacts were showing up in the BB.
Is this a Microsoft version issue, server issue, hardware issue? I've spent a bit of time on the forums and search engines looking for a similar problem and cannot find anything. I have reset the phone and deleted the user off the server and re-sync'd 3 times. Same thing happens.
I have 1000+ contacts synched to Outlook on BES, but all are in one folder.
Is it possible that your user is inadvertently filtering his contacts on his BlackBerry? A filter on the device would persist through deletion and re-sync.