We recently moved our Knowledge Base to the Discourse forum we’ve had for a while. However, the “Docs” section does not show all the available categories nor articles.
But if you click on Categories > Documentation, you see a page with all the categories & articles.
If you don’t mean the sidebar and are referring to the /docs page, you need to add each category and subcategory to the docs categories admin setting, or include the relevant tags in docs tags.