Knowledgebase: Zimbra
Date completed field does not change when task status is changed
Posted by - NA - on 30 June 2009 10:12 AM
Zimbra:

If a completed task's status is changed back to incomplete on the device, the Date Completed field does not get cleared in Outlook 2003.  Task Status and Percent Complete change in Outlook 2003, but the Date Completed remains the same.
This may cause the task to look completed in Outlook 2003's list of tasks.