Setting the BuyLimit for an item to 1 results in the shop displaying for the item: (BuyLimit of 1)

Buying the item shows (BuyLimit of 0) and allows the ability to purchase again.
After the second purchase, the item shows (Out of Stock), which is the expected result after buying 1, not 2.

    "Backpack Upgrade 1": {
      "DisplayName": "Backpack Upgrade 1",
      "CraftAsDisplayName": false,
      "Shortname": "",
      "ItemId": 0,
      "MakeBlueprint": false,
      "AllowSellOfUsedItems": false,
      "Condition": 100.0,
      "EnableBuy": true,
      "EnableSell": false,
      "Image": "https://i.imgur.com/T6orn2Q.png",
      "SellPrice": 0.0,
      "BuyPrice": 250.0,
      "BuyCooldown": 0,
      "SellCooldown": 0,
      "BuyQuantity": [
        1
      ],
      "SellQuantity": [],
      "BuyLimit": 1,
      "BuyLimitResetCoolDown": 0,
      "SwapLimitToQuantityBuyLimit": false,
      "SellLimit": 0,
      "SellLimitResetCoolDown": 0,
      "SwapLimitToQuantitySoldLimit": false,
      "KitName": "",
      "Command": [
        "bpupgrade \"$player.name\""
      ],
      "RunCommandAndCustomShopItem": false,
      "GeneTypes": [],
      "SkinId": 0
    },
    "Backpack Upgrade 2": {
      "DisplayName": "Backpack Upgrade 2",
      "CraftAsDisplayName": false,
      "Shortname": "",
      "ItemId": 0,
      "MakeBlueprint": false,
      "AllowSellOfUsedItems": false,
      "Condition": 100.0,
      "EnableBuy": true,
      "EnableSell": false,
      "Image": "https://i.imgur.com/T6orn2Q.png",
      "SellPrice": 0.0,
      "BuyPrice": 500.0,
      "BuyCooldown": 0,
      "SellCooldown": 0,
      "BuyQuantity": [
        1
      ],
      "SellQuantity": [],
      "BuyLimit": 1,
      "BuyLimitResetCoolDown": 0,
      "SwapLimitToQuantityBuyLimit": false,
      "SellLimit": 0,
      "SellLimitResetCoolDown": 0,
      "SwapLimitToQuantitySoldLimit": false,
      "KitName": "",
      "Command": [
        "bpupgrade \"$player.name\""
      ],
      "RunCommandAndCustomShopItem": false,
      "GeneTypes": [],
      "SkinId": 0
    },​