When an order is downloaded into SellerExpress it is added into your "Pending Sales" section. When the order is received the amount of stock that can be listed on any of your marketplaces is reduced however your overall quantity is not reduced at this stage.
If you have a pending order in the system and take a look at the product that order is for you will notice the QTY Listed field (Marketplace tab) is lower than the Quantity by the number of products already sold. When an order is dispatched then the overall quantity is reduced matching up the Quantity and QTY Listed fields.
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