Hello
Did you implement note 1571800 on your system?
Check this information provided on this note:
"These changes add the field "Fixed Date and Qty" to the stock transfer
item. In the table control, the new column with the checkbox is
displayed at the very end.
[...]
You can use the checkbox "Fixed Date and Qty" to define that the
material requirements planning (MRP) is to refer only to confirmation
schedule lines after the availability check takes place. Accesses are
provided on the date that the availability check confirms in the
supplying plant. For underconfirmation, the confirmed dates and
quantities are different from the desired dates and quantities. You can
no longer carry out rescheduling for the relevant purchase order item."
It basically means that you can use the flag "Fixed Date and Qty" on the stock transfer to make sure that MRP will refer to the confirmed dates.
BR
Caetano