Why Equipment ID must be specified for Pick-Loaded Shipment Equipment for Equipment Assignment?

Error: The Equipment ID must be specified for Pick-Loaded Shipment Equipment

We keep getting this error whenever we do the following

1. When using ASSIGN BEST EQUIPMENT as Agent Action on SHIPMENT agent , we keep getting this error : The Equipment ID must be specified for Pick-Loaded Shipment Equipment.
2. The same error is also thrown when doing user action on Buy Shipment via Fleet Management > Assign > Equipment. If we give Equipment Gid by manually selecting it in the Assign Equipment to Shipment pop up, the Equipment is selected and assigned. But Show Options on the same pop up does not show available equipment options.