In the Get shipment Lines page in a Sales Invoice, the filed Order No is not able to be sorted or filtered on. Is there a reason for this? It seems like every other field can be sorted and filtered on. Is this a bug?

In the Get shipment Lines page in a Sales Invoice, the filed Order No is not able to be sorted or filtered on. Is there a reason for this? It seems like every other field can be sorted and filtered on. Is this a bug?
Its not filtering because in standard system they are showing the values in variable, that is not the actual field of the table. You will not be able to filter on Order No. field.