How to show Item.Manufacturer Part Number in Purchase Order Item?

I have added a field which is READ ONLY field, and option is item_code.manufacturer_part_no and checked in_list_view, but I didn’t see any happen in Purchase Order or Purchase Order Item Form.

What’s wrong?

Moreover, I use this method in other doctype, the field shows successfully, but, it’s only show after I choosing related field, could it load synchronously?

@nnylyj the item table is customized: https://github.com/frappe/erpnext/blob/develop/erpnext/templates/form_grid/item_grid.html