Ok, found a solution, but i don't understand why this is the way it is.
in this file : extensions\igniter\local\components\menu\grouped.php
on line 33
class="collapse <?= $index < 5 ? 'show' : ''; ?>"
so any menus above 5 are hidden, but the category names are not. my best guess is that it is supposed to hide the full list above 5.
i raised 5 to 20, for me that is workable.