Board Thread:Support Requests - Getting Started/@comment-34201470-20180425145932/@comment-168424-20180425190634

Beware that not all categories show in the Source editor with the rest of the wikitext. Some may show in the CategorySelect UI on the right side while editing.

Also, category code doesn't always appear at the bottom. Lastly, categories can also get added by templates or other ways, so that's why you may see pages in categories that don't obviously appear while editing.