Est. Unit Cost of a Serialized Item on a negative Inventory Adjustment is at Average Cost.
Please note that for a Serialized Item which uses Specific Costing as Costing Method, specific costing is still followed on an Inventory Adjustment.
At saving time of an Inventory Adjustment, Est. Unit Cost is set at Average Cost. After few seconds, refresh the page and notice that the Average Cost will be changed to the appropriate Specific Cost of the Serialized Item.
Note: Average Costing Method became available for Serialized and Lot Numbered Items in 2013.2 version.
Related cases may be attached to Enhancement #231711 - Serialized Item: Transactions > Inventory > Adjust Inventory > To show Specific Cost of the Serial Number to be deducted in the Unit Cost or Est. Unit Cost column prior to saving the Inventory Adjustment