A Shopify Plus user built a Checkout UI Extension to display line-item properties and configured three targets: purchase.checkout.cart-line-item.render-after, purchase.thank-you.cart-line-item.render-after, and customer-account.order-status.cart-line-item.render-after. Only the checkout target can be enabled in the checkout editor; the thank you and order status targets are not available.
Clarification confirmed the store is on Shopify Plus and using an app. No configuration issue was identified.
Latest update: The thank you and order status page extension points appear not yet rolled out. A Shopify newsletter notes the launch of checkout extensibility for those pages was moved from October 24, 2023 to November 7, 2023.
Interim workaround: For now, modifying the thank you page may only be possible by injecting custom JavaScript via settings/checkout.liquid.
Status: Pending platform rollout; resolution expected after the new launch date. An attached screenshot is referenced but not essential to the conclusion.