Inventory is available only for base products and kits in Eshopbox. For virtual kit, you’ll always see zero inventory.
This is because the virtual kit is not a physical product available at the fulfillment center. It is a combination of multiple base products. A virtual kit is available only when they are picked and packed together after an order is received.
To check the inventory of the virtual kit, you can check the inventory of its components. In case, any one of the components is out of stock; the virtual kit will also be out of stock on the sales channel.