Default Taxonomies empty

You may need to use the code examples at https://docs.pluginize.com/article/17-post-types-in-category-tag-archives as it sounds like the post type isn’t being considered yet for the query and the category term archive.

yes now it worked!
Have I to leave this function into my theme?

Yes, it needs to persist somewhere, whether it be a theme, or a really quick custom plugin if you’re interested in that route.

For a custom plugin, all you’d really need to do is save the exact same code into a dedicated file in the plugins folder, and then add a plugin header comment, that you could copy/paste/edit from a different plugin. Then it’s just a matter of activating.

thanks!

Welcome. Let us know if you need anything else.