3 Level Deep Navigation Menu Not Showing All Levels

Question

I have a 3 level deep navigation menu which will show beside all pages on the site except the homepage. The issue is only 2 of my 3 levels are showing in the menu when displaying it using the wp_nav_menu. I've tried specifying the depth parameter and without it to no avail. I am using the Roots theme if that helps.

See below for an image as to how the menu is in the Appearance > Menus section.

The problem as can be seen from above is that "Production Solutions" and "Avalanche" are showing, but the children items underneath Avalanche aren't showing. And it's not a styling thing either the 3rd levels just aren't being output at all. I'm not using any custom walkers or anything either, this is via stock register and display nav menu functions.

This is the code that registers all of my nav menus:

register_nav_menus(array(
    'accordion_navigation' => __('Page Accordion Navigation', 'roots'),
    'footer_navigation_left' => __('Footer Navigation Left', 'roots'),
    'footer_navigation_solutions' => __('Footer Product Solutions', 'roots'),
    'footer_navigation_news' => __('Footer News & Events', 'roots'),
    'footer_navigation_about' => __('Footer About', 'roots')
));

In my page template I have this code for displaying the menu:

wp_nav_menu(array('theme_location' => 'accordion_navigation'));

Am I missing something here?