Why Planned Orders in Supplies and Demands show blank Suppliers?

Summary:

This is in Supplies and Demands screen in a Supply Plan. Users want to release Planned Orders based on Suppliers. They want to search the Planned Orders based on Suppliers by putting the Supplier in the Search criteria. But the results show no records. When they search WITHOUT the supplier in the search criteria, they get many results but with the Supplier column as blank. How to get the results of Planned Orders based on Supplier?

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