SAP BW- DTP Filter not allowing more than 990 multiple single Values

SAP BW System - 730 SP10

This is a production system issue. I am using DTP Filter option to exclude multiple Purchase Order numbers. Currently the DTP has exact 990 PO values in the exclusion list and I have received a request to exclude few more POs (say 10-15 more POs that i need to exclude). However, DTP is not accepting even one more value in the PO exclusion list. Evidently, I can exclude more than 990 POs in BW QA system, which is also 730 SP10.

Any help is greatly appreciated.

Sujal