MRP run issue in PP/DS

Hi Experts,

We are facing an issue where daily MRP( SAP_MRP_001) run for a product at vendor location.

Pur req's are created on the daily run from Production planning Run.

Issue we are facing is MRP run is not deleting the past Pur req's and creating the pur req's accordingly.

But if i run the product heuristic the Pur req's do clear and it update accordingly.

MRP Heuristic is running with reuse mode - Use suitable reciept elements.

Any inputs on the issue please.

Regards

Maddy