Maybe there is something wrong with a data model... This is the part of it:
[Comp] & ' | ' &
[Entry No_] & ' | ' &
[Transaction No_] & ' | ' &
[Posting Date] & ' | ' &
'Customer') AS [%.C.ID]
End_Date tries to reach the Due date through a LinkTable, maybe it is difficult for it?
It's difficult to say if this is the reason - it will be depend on the available keys if it could work - but I would seriously consider to change the datamodel.
Another important part related to set analysis is that fields must have exactly the same format, for example by month 2 wouldn't match to Feb and by date-fields it's the same.