Dash app works correctly on app restart, then stops displaying results

I got this one time, but now it’s happening in a second app.

The code is working fine, I can see the logs, but the UI shows the spinner, and after the code completes, nothing appears in UI.

On restart it works great, but only temporarily.

Has anyone had this happen before?

Here’s an example:

https://adver.tools/schema-generator/

Try with:

Happy to share the code if needed, but I’d like to know if anyone else faced such an issue?

It happened using dash versions 2 and 3.

Thanks