Cart Transform Function returns correct expand output but no bundling or price adjustment in Checkout for one store

Functions
1

Hey everyone :waving_hand:

We’re facing a strange issue with a Cart Transform Function (expand operation) that only happens on one large production store.

Problem Summary

Our Cart Transform Function is:

  • Returning the correct expand operations

  • Returning the correct fixedPricePerUnit adjustments

  • Executing successfully (no runtime errors)

But on checkout:

  • Bundling is not applied

  • Cart lines appear ungrouped / incorrect

  • The price shown is taken from Shopify’s variant price

  • The function price adjustments are ignored

This works correctly on other stores using the exact same function and logic.

Checkout Screenshot

CleanShot 2026-02-03 at 14.16.27@2x
CleanShot 2026-02-03 at 14.16.27@2x902×368 14.5 KB

Function Output

This shows how the cart is expanded correctly via the function output, but checkout still displays original variant prices and does not reflect bundled pricing.

Here is the function response we return:

{
  "operations": [
    {
      "expand": {
        "cartLineId": "gid://shopify/CartLine/852a9758-a75f-4346-9c5f-36a60c778f3f",
        "expandedCartItems": [
          {
            "merchandiseId": "gid://shopify/ProductVariant/47381635858683",
            "price": {
              "adjustment": {
                "fixedPricePerUnit": {
                  "amount": "41.4"
                }
              }
            },
            "quantity": 1
          },
          {
            "merchandiseId": "gid://shopify/ProductVariant/47381633859835",
            "price": {
              "adjustment": {
                "fixedPricePerUnit": {
                  "amount": "39.6"
                }
              }
            },
            "quantity": 1
          }
        ],
        "image": null,
        "price": null,
        "title": null
      }
    },
    {
      "expand": {
        "cartLineId": "gid://shopify/CartLine/c3c73a0d-348f-497e-ab1a-83fda6af1f19",
        "expandedCartItems": [
          {
            "merchandiseId": "gid://shopify/ProductVariant/47381635858683",
            "price": {
              "adjustment": {
                "fixedPricePerUnit": {
                  "amount": "39.1"
                }
              }
            },
            "quantity": 1
          },
          {
            "merchandiseId": "gid://shopify/ProductVariant/47381633859835",
            "price": {
              "adjustment": {
                "fixedPricePerUnit": {
                  "amount": "37.4"
                }
              }
            },
            "quantity": 1
          },
          {
            "merchandiseId": "gid://shopify/ProductVariant/47381631271163",
            "price": {
              "adjustment": {
                "fixedPricePerUnit": {
                  "amount": "39.1"
                }
              }
            },
            "quantity": 1
          }
        ],
        "image": null,
        "price": null,
        "title": null
      }
    }
  ]
}

What We’re Observing

  • Checkout UI shows original variant prices
  • Expand operation output is ignored in checkout
  • Bundled grouping is not respected
  • Behavior is store-specific

What We’ve Already Verified

  • Function deployed correctly
  • Function logs confirm correct output
  • Same function works on multiple other stores
  • No Shopify Scripts present
  • No automatic/manual discounts applied
  • Happens consistently on this store

Questions

Has anyone experienced cases where:

  • Checkout ignores Cart Transform expand results?
  • Certain checkout configurations, markets, or store flags block transform pricing?

Any debugging ideas or known Shopify edge cases would be extremely helpful :folded_hands:

Thanks!

1 Like
2

Hi @prakhar

Sounds like this issue is just happening on one specific store and other stores are not impacted? DMing you to collect more info.