"Overdue Today" in the Lender work queue shows requests that are shipped and the due date has been reached (so they have not yet been actioned Overdue, but are ready to be). It does not show requests that have actually been actioned Overdue.
Once you have actioned requests Overdue, you can retrieve them using the Advanced Search by selecting:
Your Library's Role = Lender (Responder)
Status = Overdue