Good luck and happy holidays 

In my case, a Shopify+ store with an unlocked checkout.liquidI generated and published the default extension code (banner) but it is not displayed. 

I uploaded the app to Heroku, the result is the same 

I haven't solved this problem yet, I've been working on other tasks. But I was hoping to get a clear answer from Shopify support I also received an email from the developers, they asked for more details of my problem. But I think the answer will be ...

we have a situation exactly as you described - an application on fly.io, it works, but the extension is not displayed in the checkout.I also wrote to support, but no answer (((I see that lately there are almost no answers from Shopify experts. Did y...

Hey Nicolas. Faced the same problem. It is not clear how to make the extension work on the live store. Let me know if you made it.