Checkout blocks will not save — editor Save does not stick.

Several “checkout customization broken” bugs look alike. They do not share a fix. This page is only when you can open the checkout editor, add or edit a block, click Save, and the change does not stick on reload or on live checkout. Extension installed but never mounts / blank on checkout is shopify-checkout-ui-extension-not-loading. Placement / target deprecated so the block never appears in the picker is shopify-checkout-ui-extension-target-missing. Editor cannot open or is fully locked is shopify-checkout-editor-locked. Branding tokens / colors / fonts not applying is shopify-checkout-branding-api-not-applying. Thank-you surface customization missing is shopify-thank-you-page-customization-missing. Post-purchase page not loading is shopify-post-purchase-page-not-loading.

Soft links when the bug is adjacent: unfinished checkout.liquid → Checkout Extensibility migration is checkout-extensibility-upgrade-broken. This playbook stays on checkout editor Save expected to persist block config → Save toast / reload / live checkout proves the block vanished or reverted → draft never published or Save never succeeded.

Open Settings → Checkout → customize (Checkout Extensibility editor). Confirm you are on the correct checkout profile for the market / channel you care about. Add or edit one block, click Save, and watch for a success toast vs an error. Open DevTools → Network on the Save request and note 200 vs 4xx/5xx. Hard-refresh the editor. Open a private-window live checkout and confirm whether the block is present.

Check staff permissions: the logged-in user needs checkout / Online Store edit rights appropriate for your plan. Plus gates still apply for some checkout surfaces — if the editor opens but Save silently no-ops, treat permissions and plan as suspects. Note whether a second staff member had the same profile open (last writer wins). Capture screenshots of before Save, after Save toast, after hard refresh, and live checkout.

Soft-check: if the block never appears in the picker / target list, leave this page for shopify-checkout-ui-extension-target-missing. If the editor will not open at all, use shopify-checkout-editor-locked. If Save sticks in the editor but the live checkout never mounts the extension, use shopify-checkout-ui-extension-not-loading. If only branding tokens fail, use shopify-checkout-branding-api-not-applying.

If Save only updates a draft checkout profile, publish / set the profile live for the Online Store channel. Reinstall or update the Partner app that owns the block so the schema matches what the editor expects. Fix staff role permissions or use an owner / full-access account for a control Save. Close duplicate editor tabs and ask other staff to leave the profile while you Save.

Temporarily disable other checkout UI / Functions apps fighting the same surface. If Save returns 4xx/5xx, retry after a short wait and check Shopify status. If the store never finished the checkout.liquid retirement, repair that path on checkout-extensibility-upgrade-broken first, then return here only if Save still does not persist when Extensibility is healthy.

Retest: add one known-good block → Save success → hard refresh editor still shows the block → private-window live checkout shows the block. Soft notes: extension blank on live belongs on shopify-checkout-ui-extension-not-loading. Target missing belongs on shopify-checkout-ui-extension-target-missing. Editor locked belongs on shopify-checkout-editor-locked. Branding belongs on shopify-checkout-branding-api-not-applying. Thank-you belongs on shopify-thank-you-page-customization-missing. Post-purchase belongs on shopify-post-purchase-page-not-loading.

Checkout UI extension not loading is shopify-checkout-ui-extension-not-loading. Target missing is shopify-checkout-ui-extension-target-missing. Editor locked is shopify-checkout-editor-locked. Branding API not applying is shopify-checkout-branding-api-not-applying. Thank-you customization missing is shopify-thank-you-page-customization-missing. Post-purchase not loading is shopify-post-purchase-page-not-loading. Extensibility upgrade broken is checkout-extensibility-upgrade-broken.

The only honest test for this page: checkout editor Save → hard refresh still shows the same block config → live checkout reflects it (or you prove Save never succeeded / draft never published). Anything else is a different product.

Stay DIY if you can spend one afternoon on the list above: prove Save toast vs network error, draft vs live publish, staff permissions, single-editor concurrency, retest one block through live checkout. That is the whole playbook. No agency required. Short answers also live on the merchant FAQ. Related pages: extension blank, target missing, editor locked, branding, thank-you, post-purchase.

Pay for help when the work is not the Save button itself — it is connecting the stack you already have so checkout / block / save 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-editor 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.