They are in the Other category for its gray color. The code still says they're in the Other category, but they aren't shown in the Other category.
If I were to make one, I wouldn't need the code. But if I didn't, and there were custom blocks in it, I'd want the category switching to scroll to the Other category when I click its button. But if there are no custom blocks in it, I want it to scroll to the Lists category.