I created a new page, “TEST”, and inserted the shortcode of the created category. The new page is displayed, as well as the contents of the category created.
https://www.polocattaneo.it/istituto/test/
But when you click on the content to read it entirely (read more) it is not displayed, and the message Oops appears! That page can not be found.
It looks like nothing was found at this location. Maybe try a search?