It is a bit stupid question, but have you double-checked that the material was not changed after the order was created? And that this is the same sales org/distribution channel?
If this is the case, then probably you can check for custom developments - mv45afzz - move_field_to_vbap is a good place to start looking.
Edit: is the order created manually in ERP - VA01 or it originates from a different system / is generated with a special program?
Message was edited by: Veselina Peykova