Following up on the bug Joining a group doesn't take effect unless the browser is hard-refreshed - it seems there are a couple of important category lists that don’t get updated when a user joins a group that enables access to a category.
In the below example, the sidebar and category list on the topic editor didn’t contain the “Politics” category despite the user joining a group that enabled access to this category. A browser refresh was required to see the updated list of categories.

