Hello,
Did you execute report SDRQCR21?
Run the report SDRQCR21 in transaction code SE38 for the material and check transaction code MD04 again
I think you are using MTO planning strategy.
MTO sales order is completed/delivered, but the sales order special stock is still displayed on MD04.
The solution for this issue is outlined on note 1723507.
Read KBA 1723507 - Completed sales order special stock is displayed on MD04 / MD05
Best Regards,
R.Brahmankar