When a item record is pulled up, the where used tab selected, the current values of the where used are not a true representation of the actual production BOMs. It shows the superseeded values (also shows it's reporting to production lifecycle) and obsolete items (also shows the lifecycle is a production value).
Please add a filter to remove any superseeded or obsolete items and their quantities. These values are not a true representation of the "active production lifecycle" where used.