Issue: Cost price updates only after sold out the purchased products, is it correct or not?

Here is the example:

1. Created a product1 as cost price 0.0.
2. Created landed costTravel as cost 100, split method =equally.
3. Created Purchase order for product1, and received products and registered payments. Ex: 5 qty, cost= 100, Total cost=500
4. Created Landed costs from Inventory module.
5. Added stock move and landed costs and validated successfully.
6. Noe total Inventory value = 500+100=600
7. Price per product = 600/5=120

8. Now if i check cost price in product form, still 0( Is it correct?, it should update?).

9. If i create a sale order with qty of 5 and complete payments and delivery, the cost price will update to 120.

10. But now i have 0 products left.

Please help me to understand the landed price and cost price update ?