Anyone else having this problem? I've seen this problem from just upgrading from 2007 to 2010. Folders or objects in folders just "get stuck" and don't sync to the server. Users have no idea that their data is vulnerable. No errors logged anywhere. Just data missing from the web U/I but there in OL.

Steps to reproduce:

1. Using Outlook 2010, attach a PST file from a previous version of Outlook
with Contacts
2. Copy some of the 2003/2007 contacts from the PST file to the current
contacts folder
3. Sync
4. Go to web U/I to confirm that these contacts appear in the address book

It is a supported way – it just doesn’t work in Outlook 2010. Neither
Import nor Open Outlook Data File and copy/paste works in 2010. It also
doesn’t matter whether the PST was generated with Outlook 2003/2007. Even if you generate it with 2010, it won’t sync. ZCO is not picking it up as a
valid change, so we’re not creating a change record for it.

Bug 51869 – Import contacts using OLK 2010