When viewing "Customer & leads" > Overview it shows overdue invoice total far below actual overdue value.  Why? 

In the attached example look at lot 113.  Overview shows it at $335 overdue, but when I look at this same customer using "Customer & leads" > Customer   for Lot 113 it is far greater.   

It is like the Overview report is only picking up last year's overdue invoices when it should be picking up ALL overdue invoices.