Qty Delivered for column for internal requisitions not populating and showing as 0.

For internal requisitions (stock orders) where sales orders are generated, we have noticed the'Qty Delivered' field is not being populated. As far as we can see all necessary processes are running to populate this (we think). So my question is what is required for an internal order to show as delivered, both from a process point of view and also system point of view, e.g. concurrent requests.

Thanks in advance,
Adam