I have tried your site on my mobile and the all the categories open okay.
To see all the characters on the menu take a look at the following:
If you want to have all the categories closed on mobiles you can modify line 12 in main/views/themes/tastyigniter-orange/partials/menu_list.php to this:
<div id="<?php echo $category_name; ?>" class="navbar-collapse collapse <?php echo ($category_count === 0) ? 'in' : ''; ?>