Shopify checkout UI extension not loading — or the checkout extensibility block never appears.

Several checkout products can look like “something is missing next to pay.” They do not share a settings panel. This page is only when a checkout UI extension or checkout extensibility app block does not load in Settings → Checkout → customize, or never appears on the live checkout surface it was built for. Tip / gratuity missing is shopify-tip-at-checkout-not-showing. Delivery / scheduled delivery picker missing is shopify-delivery-date-picker-missing. Shop Pay / dynamic checkout button missing is shopify-shop-pay-button-missing. Admin / app webhook delivery failure is shopify-webhooks-not-delivering. Blank thank-you / order status page is shopify-order-status-page-blank. The post–checkout.liquid Checkout Extensibility upgrade broken playbook is the migration / thank-you attach failure — this page is the day-to-day UI extension / app block that will not load.

Six ordinary reasons the block never loads: the app is not installed or the extension is disabled, you are editing a draft profile while buyers hit a different published profile, the extension target does not match the surface you are staring at, the store plan does not expose that Plus-gated checkout surface, you installed a Shopify Function (discount / delivery / payment customization) and expected a visible UI block, or a browser / ad-blocker / checkout preview session is hiding the block while production is fine.

Checkout UI extensions and checkout editor app blocks live on a checkout profile. Open Settings → Checkout and confirm you are customizing the published / live profile — not a draft, not a Markets-specific profile buyers never hit, not a Plus checkout customization surface your plan does not offer. Non-Plus shops still get many information / shipping / payment UI extension targets; some advanced customizations and legacy Script-era behaviors are Plus-gated. If the app’s docs say Plus-only and your plan is Basic / Shopify / Advanced, the block will never appear no matter how many times you refresh the editor.

Read the extension’s target (for example purchase.checkout.block.render, shipping option list, payment method, thank-you, order status). A block built for thank-you will not show on the information step. A delivery customization Function will not draw a date picker UI by itself — that usually needs a separate checkout UI extension or a third-party app block. Capture: plan name, which profile is published, which target the app claims, and whether the block appears in the editor’s “Add app block” list at all.

Also confirm the app install is on this shop (not a staging shop), the extension is enabled in the app’s admin, and you are not previewing checkout while logged into a staff account that skips the buyer path. Staff / custom checkout preview sessions sometimes hide buyer-facing app blocks.

In the checkout editor, use Add app block (or the app’s documented placement) on the live profile. If the block is absent from the picker, update or reinstall the app, accept new scopes, and check Partner / app version notes for a broken extension release. If the block is present but blank on live checkout, publish the profile after edits — draft saves do not ship to buyers.

Do not confuse Shopify Functions (automatic discounts, cart transform, delivery / payment customizations) with checkout UI extensions. Functions change logic and rates; UI extensions render visible blocks. An automatic discount Function that is “not applying” is a different playbook (shopify-functions-discount-not-applying). Scripts → Functions migration is shopify-scripts-to-functions-migration. This page is only the visible checkout UI extension / app block that will not load.

After publish: open an incognito buyer checkout (not the admin preview alone), hit the same market / currency / shipping method the block depends on, and confirm the block renders before pay. If it only fails on one market or one payment method, check Markets / checkout profile assignment and any app setting that gates the block by country or cart contents. Disable conflicting checkout UI extensions that claim the same slot if the editor shows overlapping blocks.

Tip at checkout missing or not saving is shopify-tip-at-checkout-not-showing. Delivery date / scheduled delivery picker missing is shopify-delivery-date-picker-missing. Shop Pay / dynamic checkout button missing is shopify-shop-pay-button-missing. Webhook delivery failure is shopify-webhooks-not-delivering. Blank thank-you / order status is shopify-order-status-page-blank. Checkout Extensibility upgrade / thank-you attach after checkout.liquid retirement is checkout-extensibility-upgrade-broken.

The only honest test for this page: app installed and extension enabled, published checkout profile, correct UI extension target / app block on that profile, plan allows the surface, profile published after edits, buyer (not staff-only) checkout shows the block. Anything else is a different product.

Stay DIY if you can spend one afternoon on the list above: confirm Plus vs non-Plus eligibility, edit the published checkout profile, place the app block on the correct target, stop confusing Functions with UI extensions, publish, and retest as a buyer. That is the whole playbook. No agency required. Short answers also live on the merchant FAQ. Related pages: Extensibility upgrade, tip at checkout, delivery date picker, Shop Pay button, Functions discount.

Pay for help when the work is not the checkout editor toggle — it is connecting the stack you already have so lead capture is not dying in DMs, storefront and checkout-ready exceptions land in a channel you already check, and the live store is one workflow instead of a spreadsheet plus a Slack bot you forgot. That is the Latch AI Ops install.

What $997 USD one-time buys: lead capture on the live store, ops alerts in a channel you already check, and a checkout-ready workflow. 72 hours after collaborator access, not after payment. One live Shopify store. Access plus a delivery thread. Store URL collected at checkout. Not a SaaS seat, not a theme rebuild retainer, not a conversion guarantee, not a brand or theme job.

Other shops’ public ranges, not testimonials: a checkout / ops install typically runs $500–$2,500. A full ops consulting block typically runs $2,000–$5,000. $997 is the cheap end of that work, sold as a 72-hour install of three systems — not as an earnings number or conversion-lift claim.

What it does not buy: more orders, recovered revenue, a forever checkout-extension uptime guarantee, or a case study. Latch AI Ops has not published customer proof because there are no customers yet. You are buying the install.

Checkout is on Whop. Operator is Nico. United States offer. You can revoke collaborator access after handoff. We do not take owner passwords.