Taxonomie showing up with no entries

To be certain, are you meaning the terms are not showing up on the frontend, say in a comma-separated list alongside other data about the post?

Or that the term archives aren’t showing the posts in their listing?

Or that they’re not displaying as a checkbox listing when editing the post?

Trying to determine exactly what issue you’re looking for help with.

the terms are not displaying as a checkbox listing when editing the post… there is only a field to add “new terms”.

Set the taxonomy to have the “hierarchical” dropdown set to true, and you should get those checkboxes.

Yes! Working! so easy ??
Maybe you know also how i can insert my new taxonomie terms within a new post?
Is there a custom tag?

Displaying set terms for a given post is going to be a template/theme thing needing done. There are definitely functions around fetching and creating output for the terms, but it’s not something we have built in to our plugin here.