Hi Mohammed
Please elaborate more on your issue.
However based on your statements above, I understand Sales orders are fully invoiced and costs which are settled via service orders to Sales orders are still reflecting as WIP amount and should actually be posted as COGS.
If my understanding is correct, check the status of the sales order. In OKG3, based on the status, the appropriate valuation is considered and then settled to FI, as the case maybe.
Hope it helps
Regards
Mustafa