Multiple currencies
Affected by: Plus (Cart Transform) method If your store uses Shopify Markets or a third-party multi-currency app (e.g. Global-E, Currency Converter Bear, Auto Currency Switcher), do not run Plus price tests.Why it breaks
Cart Transform applies the price adjustment in your store’s base currency. When Shopify converts this to a foreign currency for display, the conversion happens after Cart Transform runs. This creates a mismatch:- The
data-spt-priceattribute updates the displayed price in the base currency amount - Shopify’s currency conversion converts the original price from the product — not the Cart Transform price — for display in the storefront header
- The customer may see one number on the product page and a different number in the cart
Workaround
Use the non-Plus duplicate product method instead. The test price is set directly on the product in Shopify Admin and goes through the same multi-currency conversion as any other price. It works correctly regardless of which currency the visitor has selected.Subscription products
Affected by: Plus (Cart Transform) method Shopify does not allow Cart Transform functions to modify the price of line items that have a selling plan (subscription) attached.What happens
If your product offers both a one-time purchase and a subscription option:- Visitors who click Add to cart on the one-time option → Cart Transform applies the test price correctly
- Visitors who select a subscription option → Cart Transform is ignored for that line item → the original price is charged
Workaround
Do not run Plus price tests on subscription products. If you want to test pricing on a product that offers subscriptions, use the non-Plus duplicate product method. Since the price is set directly on the product, it applies to all order types including subscriptions.Page builder product pages
Affected by: Plus (Cart Transform) displayed price update If your product detail page (PDP) is built with a page builder app — Replo, PageFly, Funnelish, GemPages, Shogun, or similar — the HTML structure it generates often does not match the standard price element selectors.What happens
Arktic’s price script looks for elements withdata-spt-price (product page price) and data-spt-cart-price (cart price). In Shopify-owned themes, these are added automatically. In page builder components, the price element is generated by the page builder’s rendering engine with its own custom markup.
The result: the visitor is assigned to the test variant, but the displayed price on the product page does not change. The Cart Transform function still runs at checkout (so the customer is charged the correct price), but the displayed price is wrong — a trust and UX issue.
Fix
Add thedata-spt-price attribute to the price element inside your page builder component:
- Replo — select the price text element, open the Settings panel, and add a custom attribute
data-spt-price - PageFly — select the price element, open Advanced → Custom attributes, add
data-spt-price - Funnelish — use the custom HTML widget to wrap the price element with the attribute
- Other builders — refer to your page builder’s documentation for adding custom HTML attributes to elements
JavaScript and app-based bundles
Affected by: Plus (Cart Transform) method If your store uses a bundle app that adds products to the cart through its own JavaScript (rather than through a standard Shopify product form), thespt_asgn cart attribute may not get attached to the cart during the add-to-cart action.
Why it breaks
Arktic writes the cart attributespt_asgn on every page load via /cart/update.js. This happens independently of the add-to-cart action, so in theory the attribute is always there. The issue arises when a bundle app performs its own /cart/add.js call and then immediately takes the visitor to checkout without going through a cart page — in this flow, the page load that would write the attribute may not have happened.
Bundles that work correctly
- Shopify’s native bundle (product bundles with components) — standard product form, works correctly
- Bundles set up as separate products in Shopify Admin — treated as regular products, works correctly
- Bundle apps that add to cart via a standard product form submit — works correctly
Bundles that may not work
- Apps that add multiple products to the cart via direct AJAX calls and then redirect to checkout
- Subscription apps with custom checkout flows that bypass the cart entirely
- Custom “build a box” flows that use their own checkout sessions
Fix
Test your bundle flow manually:- Add a product to cart via the bundle
- Open
/cart.jsonin the browser - Check
attributes.spt_asgn— if it is set, Cart Transform will work correctly - If it is not set, contact us to discuss a custom integration
Headless and custom storefronts
Affected by: All price testing methods If your store uses a headless frontend (Shopify Hydrogen, a custom React or Vue storefront, or a third-party headless solution), the Arktic theme app extension script does not load — it is only injected by Liquid templates. The embedded script (/storefront/embed.js) is available as a direct script tag you can add manually, but cart attribute writing and DOM price updates require custom integration.
Contact us before running any experiments on a headless storefront.
Dynamic pricing apps
If you use an app that dynamically reprices products (volume discounts, customer-specific pricing, B2B pricing), the prices shown on your product page may already differ from the base Shopify product price. Running a price test on top of this can produce unpredictable results — the displayed price and the Cart Transform price may both be modified by different systems. Test this manually before running a live experiment.Not sure if your store is affected?
Email us at info@arkticstudio.com before launching a price test and we will check your specific setup. Include:- Your store URL
- Which price testing method you plan to use
- Any apps you use for bundling, subscriptions, or currency conversion