Contents of Offline Client PST do not seem consistent with contents of Archive Manager mailbox.
A full resynchronisation of the Offline Client PST may resolve the inconsistency.
To perform a full resynchronisation of the Offline Client PST, follow these steps:
1. Turn off Offline Client Cached Mode from within Outlook
2. Close Outlook
3. Navigate to the following location on the machine that requires full resynchronisation of the Offline Client PST.
4. Rename the folder contained within the above path from its system generated name, which will be similar to "ECC55811051C75DED660844652AAD0EF", change this name to "PSTold".
5. Start Outlook
6. Enable Offline Client Cached Mode and allow the Offline Client to full resynchronisation of the Offline Client PST.