GraphQL mutation to create a Shopify BXGY automatic discount with all products selected failes

I am creating a Shopify app and using a GraphQL mutation to create a BXGY automatic discount. The mutation works fine when I specify a specific product in the customerBuys.items field. However, when I remove the products field from the customerBuys field and set customerBuys.items.all to true (to apply it to all products) I get the following error:

{
  "discountAutomaticBxgyCreate": {
    "userErrors": [
      {
        "field": [
          "automaticBxgyDiscount",
          "customerBuys",
          "items"
        ],
        "message": "Items in 'customer buys' must be defined",
        "code": "BLANK"
      }
    ],
    "automaticDiscountNode": null
  }
}

I’m not sure why this error is happening, as I have followed the Shopify API documentation correctly. Could this be a problem with the Shopify API or is there something wrong with my mutation?

My Mutation:

mutation CreateDiscount($amount: Decimal!, $productId: ID!) {
        discountAutomaticBxgyCreate(automaticBxgyDiscount: {
            title: "BXGY discount test",
            startsAt: "2022-01-01",
            endsAt: "2024-04-18T02:38:45Z",
            usesPerOrderLimit: "1",
            customerBuys: {
                value: {
                    amount: $amount
                }
                items: {
                    all: true
                }
            },
            customerGets: {
        value: {
            discountOnQuantity: {
            quantity: "1"
            effect: {
              percentage: 1
            }
          }
        }
                items: {
                    products: {
                        productsToAdd: [$productId]
                    }
                }
            }}) {
            userErrors {
                field
                message
                code
            }
            automaticDiscountNode {
                id
                automaticDiscount {
                ... on DiscountAutomaticBxgy {
                    title
                    summary
                    status
                }
                }
            }
        }
    }

Any help or suggestions would be appreciated. Thank you!

I’m trying to use this API with very simple parameters and every time it gives Request Error, even this most simple version:

mutation {
  discountAutomaticBxgyCreate(automaticBxgyDiscount: {
    combinesWith: {
      orderDiscounts: false,
      productDiscounts: true,
      shippingDiscounts: false
    },
    customerBuys: {
      items: {
        all: true
      },
      value: {
        quantity: 2
      }
    },
    customerGets: {
      items: {
        all: true
      },
      value: {
          percentage: 0.3
      }
    },
    title: "Buy 2 Get 1 Free"
  }) {
    automaticDiscountNode {
      id
    }
    userErrors {
      field,
      message
    }
  }
}

The answer always is:

{
  "errors": [
    {
      "message": "Internal error. Looks like something went wrong on our end.\nRequest ID: 52a4672d-e8bb-4685-bc5f-ad6b979e37ad (include this in support requests).",
      "extensions": {
        "code": "INTERNAL_SERVER_ERROR",
        "requestId": "52a4672d-e8bb-4685-bc5f-ad6b979e37ad"
      }
    }
  ]
}