When listing, my app don't up in iframe

[George8]

Hi.

I'm having a problem with listing.

I've created an application using the Remix template. Deployed it to the server. Everything works, on my side : Installation, scopes confirmation, adding extensions to the theme.

But when listing, the shopify team encounters a problem. They do not see the UI of my application, it does not appear after installation. They see "The connection was reset". At first, they gave a link to the documentation on setting up OAuth. But according to the documentation, this functionality is built into the template. Then they replied:

"That the issue they encountered was related to Cloudfare. This refers to our application configuration errors, which in most cases clearly indicate that the problem is internal to the application and not in the network. This error prevented our team from continuing and testing your application further, so it was rejected."

We don't use Cloudfare at all.

The problem is that I cannot reproduce this issue, it is only on the Shopify team's side. And I do not get a clear answer why this could happen.

I would be very grateful if someone could suggest why this could happen.

Perhaps there are some nuances in installing the application when listing?

Maybe I missed something in setting up the application?

Is it necessary to use a Cloudfare tunnel?

Are there any special features in setting up the server?

Any ideas.

Thanks in advance.