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.
You have access to that category (you could type it in your browser and go there), but it’s not reflected in your browser because that list of categories was loaded before you had access to the group. You just have to hard-reload when you join a group.