If you’re aiming for this outcome rather than #uncategorized as your deafult you should be safe creating a new #general category, moving all of your #uncategorized topics into it using the bulk tool, and then disabling allow uncategorized topics in your admin settings in preparation (though this won’t fix the dropdown).
However, this will only take a Team member a couple of minutes to fix up along with manually updating your hidden general_category_id setting so you may just want to wait. 