After importing categories via phpMyAdmin 404 on the pages of this category

Question

I imported categories (+ subcategories) via phpMyAdmin 

When I click on categories all ok. When I click on the subcategories - 404
If I add a question with a Category / Subcategory, it does not appear on the Subcategory page, only in the Category.
What could be the reason?
Thank you!

Answer 1

I decided this

After importing the rows into MySQL, you need to go to Admin→Stats→Database clean-up operations and click on the desired button for reindex.