We have different varieties of vintage electronics under one listing, and because they are vintage items, when an item sells, there may be no more available. The listings are "Listed until sold", however, periodically, Ebay apparently refreshes the listing and resets the quantity available to the original quantity. It has happened several times where an item has been purchased which had sold previously. We immediately cancel the sale and refund the buyer, however, it shows up as a transaction defect on the Sellers dashboard. We have thousands of items for sale, and to manually adjust the Ebay listing to avoid such a situation is very time consuming and impractical, particularly when Ebay does not notify that a listing has been refreshed. Use caution with Ebay listed-until-sold option with multiple items, lest you get unpleasant surprises.
