Change STO Order Qty After Partial GI & Before Full GR

Hi experts,

We encounter this error whenever we attempt to adjust the order qty to a lower qty:

Please enter a quantity that is smaller than the total quantity

Scenario:

Order qty: 2588 pcs

Delivered (GI): 2202 pcs

Received (GR): 462 pcs

Committed Qty: 2202

Importer would like to change the Original order qty from 2588 to 2202 but cannot proceed due to the error above.

There's no purchase requisition prior this STO.

Question is, is it standard behavior to hinder the changing of qty in the STO when GR qty <> GI qty? We cannot perform full GR yet since goods are not yet at the port.

Regards,

Karen