category links don't work

On my site there are 2 types of categories:

the first has link mysite.com/id-category and in this case I cannot see the content of the page (the div with id “t3-mainbody” is missing in the generated HTML code).

The second type of category has link mysite-com/category and this works.

At the same time, the articles of the first category (link like mysite.com/id-category/id-article) don’t work (the div with id “t3-mainbody” is missing in the generated HTML code), but the articles of the second category work (link likemysite-com/category/article).

I use Joomla 3.9.19 and the Purity III theme (t3 framework).

How can I fix the first type of links?