Verify and Correct Item Costs or Balances
If you'd like the system to recalculate inventory costs and first/mid/last quantities, go to Admin -> Inventory -> Verify Inventory.
After the tool runs, the system will show the item cost before and after so you can see the change in value from the tool's recalculation. (The cost method used for the Cost columns will be the one selected in Admin -> Inventory -> General Setup -> Inventory Cost Method).
The recalculation itself only happens when the report is built on screen. Downloading the results does not run the recalculation a second time, so the downloaded copy shows the same before and after values you saw on screen.