I am unable to enter the supplier in PO while doing through buyer work center

I created a PR in the iProcurement Non-Catalog Request. From the Buyer Work Center, I am creating a PO. While creating the PO, if I enter a supplier in the Document Builder, the supplier list is displayed, allowing me to choose a supplier, and the selected supplier appears after the PO is created. However, if I don’t enter a supplier in the Document Builder and create an incomplete PO, I am unable to see the supplier from list when updating the PO, and I cannot see any suppliers in this page.

Can Anyone provide the solution please