Article titles not displayed

Hello forumers. Recently I’ve discovered a failure in my wordpress page.
I have a menu where the items are categories, and my articles are enhanced to that categories. So, when you click one item from the menu, you’ll redirected to the posts that contains the category. Till here is ok.

The problem is that when I chose that category, the title of the second post is not displayed anymore…. And I don’t know why. But in the Main Page, all posts are displayed with the title.
How can it be?

Thanks in advance. The page is: https://technohow.es/category/actualidad/