Why is there no sandwich menu button on mobile resolutions?

Question

JavaScript

Greetings! There is a test site with the flatastic theme installed.
I can’t figure out why on mobile resolutions on most pages there is a top menu button-sandwich-accordion, but here in my personal account, for example, not?

home (there is a button)

<div class="container">
  <!-- - - - - - - - - - - - Main Navigation - - - - - - - - - - - - - - -->

  <div class="mobile-button" id="mobile-button"></div>
  <nav id="navigation" class="navigation">
    <ul id="menu-menyu-1" class="menu">
      <li id="menu-item-3158" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-home menu-item-3158"><a href="http://a-lot-of-money.ru/templates/22/">Главная</a>
      </li>
      <li id="menu-item-3207" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-3207"><a href="http://a-lot-of-money.ru/templates/22/vendor_dashboard/orders/">Orders</a>
      </li>
    </ul>
    <div class="clear"></div>
  </nav>
  <!--/ #navigation-->

  <!-- - - - - - - - - - - - / Main Navigation - - - - - - - - - - - - - - -->

  <a href="javascript: void(0);" class="search-button"></a>
</div>

Personal account (no button)

<div class="container">
  <!-- - - - - - - - - - - - Main Navigation - - - - - - - - - - - - - - -->

  <nav id="navigation" class="navigation">
    <ul id="menu-menyu-1" class="menu">
      <li id="menu-item-3158" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-home menu-item-3158"><a href="http://a-lot-of-money.ru/templates/22/">Главная</a>
      </li>
      <li id="menu-item-3207" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-3207"><a href="http://a-lot-of-money.ru/templates/22/vendor_dashboard/orders/">Orders</a>
      </li>
    </ul>
    <div class="clear"></div>
  </nav>
  <!--/ #navigation-->

  <!-- - - - - - - - - - - - / Main Navigation - - - - - - - - - - - - - - -->

  <a href="javascript: void(0);" class="search-button"></a>
</div>

those. the difference is actually in one line

<div class="mobile-button" id="mobile-button"></div>

Answer 1

Here, except for guessing on coffee grounds without access, and there is no desire to swear at all.
Go to the dev tools mode (developer, I explain on my fingers) - right mouse button -\u003e explore the element.
And do the same on the page where there is a button for this menu. (That is, right-click on this element and explore. There should be a class like this -
The class name will be different, but this is an example.
If there is such a class (as on the page where the menu is displayed), then you need to look at the reason. If not, then it shouldn't be.