Checkout UI Extensions Not Showing

[matthewdolman]

I have built a Checkout UI extension, and have had no problems using it in a dev environment, I would like now to install the app into a development store to test the entire process.  The rest of the app (a theme app extension and the embedded admin app) work fine, but the checkout UI extension doesn't show.

I have read from several sources that it needs to be added to the checkout by the merchant in the checkout customizer, however when I go to add the app there I get the message

"Customizing with app blocks is not available for this page. To customize branding, go to settings."  

What am I missing?

[Vijendra · Accepted solution]

did you select Checkout Extensibility when you create development store and also select test data
If helpful then please Like and Accept Solution.

[Haroon_Ahmed]

I have exact same issue.
Yes my development store supports checkout extensibility but still ui is not showing on checkout page. even though other things I am doing with the app works fine like I have two shopify functions in same app that work fine.

[deanatkard]

Hi Matt, after merchants (with plus plan) installs your app (checkout extension UI), the merchant will still manually add the UI to checkout customizer? It is a bad user experience that merchants will need to manually do something. could you please confirm it is true? thanks