Sales Order Header Information gets Null and Disappear after some time

Summary:

The issue is that the Header Information on any Sales Order disappears after a period of time and setting up new expected shipments on an order. why for some time, some of the information become NULL even if during creation of sales order, those information are complete. These incudes:
• Shipping Method
• FOB
• Warehouse
• Payment Terms
• Purchase Order Number

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