Critical regression with Function Discount API since 1st of October 2025

Functions
1

Since 1st of October 2025, about 7pm Paris time, my function using the (new) Discount API (v2025-04) started to be displayed in the checkout without any discount value (no value at all, the space dedicated to the discount value does not appear, no 0€ neither), only the label of the discount is displayed.

After checking the partner log of the function, the outputs of the function result didn’t change at all and were still valid according to the documentation. No error in the logs.

I have generate a new Discount function that only and directly apply a discount on the order of 1%. The result is the same : the discount label is displayed in the checkout, but the discount value is ignored.

This looks like a silent fail in the Shopify system, we are unable to operate any fixes nor workarounds that match 100% of the business requirements of a complexe Discount API function leading to a critical regression for Shopify Plus clients relying on this core feature for this business.

Here is a visual example :

Capture d’écran 2025-10-02 à 18.52.32
Capture d’écran 2025-10-02 à 18.52.32438×214 6.25 KB

Here is the function output from the dashboard :

{
  "operations": [
    {
      "orderDiscountsAdd": {
        "candidates": [
          {
            "message": "Debug 1%",
            "targets": [
              {
                "orderSubtotal": {
                  "excludedCartLineIds": []
                }
              }
            ],
            "value": {
              "percentage": {
                "value": "1.0"
              }
            }
          }
        ],
        "selectionStrategy": "FIRST"
      }
    }
  ]
}

(The issue occurs with fixedAmount and percentage and other values of course.)

2

Confirming the issue has been addressed by Shopify. No communication on it so the source of the bug stays a mistery.