sub-menu menu not collapsing

I am currently using material design bootstrap for styling components of my site and the side-nav layout I’m using looks like this:

<ul id="slide-out" class="side-nav fixed personal-side-nav dark-side-nav">
    <div class="logo-wrapper">...</div><!--/logo-wrapper-->

    <ul class="collapsible collapsible-accordion">
      <li><a class="collapsible-header waves-effect waves-light">Home</a></li>
     <div class="collapsible-body">
                    <ul><!--in wordpress this becomes .sub-menu but I figured out how to change the class-->
                        <li><a href="#" class="waves-effect waves-light">Sample Page</a>
                        </li>

                    </ul>
                </div><!--/collapsible-body-->
    </ul><!--/collapsible collapsible-accordion-->
</ul><!--/slide-out-->

And this is what I have in my header.php for the nav:

<?php
wp_nav_menu( array(

	'theme_location'	=> 'primary',
	'container'		=> 'ul',
	'container_class'	=> 'side-nav',
	'menu_class'		=> 'collapsible collapsible-accordion'

	) );						

?>

And this is how the code within ul.collapsible looks when it’s on localhost:

<ul id="menu-menu-1" class="collapsible collapsible-accordion"><li id="menu-item-10" class="menu-item menu-item-type-post_type menu-item-object-page current-page-ancestor current-menu-ancestor current-menu-parent current-page-parent current_page_parent current_page_ancestor menu-item-has-children menu-item-10"><a href="#">Home</a><!---I removed the link href for this forum post-->
<ul class="sub-menu">
	<li id="menu-item-6" class="menu-item menu-item-type-post_type menu-item-object-page current-menu-item page_item page-item-2 current_page_item menu-item-6"><a href="#">Sample Page</a></li><!---I removed the link href for this forum post-->
</ul>
</li>
</ul>

Here is what displays when I create a page and set it as a sub-menu item customizing the menu in wordpress:

Home
Sample Page
(the sample page is supposed to collapse an not be visible until Home page is clicked )

I’m not sure what’s causing the problem or how to fix it.

Using XAMPP for localhost.
I am using underscores.me for making a custom theme template.
I currently don’t have a site up and running right now to show the problem.