Nested Category Not Displaying in Navigation

Thanks for your suggestion, Parshant! Looking in Studio, I'm guessing the custom component I need to edit is custom.top-navigation. However, I do not see the object you refer to. This is the code:

<#-----

Creates a horizontal navigation component for desktop. At smaller view ports the slide out menu will be used instead. The component supports
between 1 - 3 levels of nesting. See documentation for visual examples.

Options:
    depth = [number] the levels of community structure to be shown in the nav
    communityLink = [true/false] show a community home link

-->
<@liaMarkupCache ttl="10000" anonymousOnly="true" />
<#include "theme-lib.common-functions.ftl" />
<@compress single_line=true>
<#assign communityLink = env.context.component.getParameter("communityLink")!"true" />

<#assign liql_query = "SELECT id, view_href, title, short_title,description FROM categories WHERE depth=1 AND hidden=false ORDER BY position ASC" />
<#assign tlc = executeLiQLQuery(liql_query) />

<#assign liql_query = "SELECT id, view_href, title, short_title FROM boards WHERE depth=1 AND hidden=false ORDER BY position ASC" />
<#assign boards = executeLiQLQuery(liql_query) />

<nav class="mds-site-navigation visible-lg-block">
    <ul class="mds-site-navigation__list">
        <#if communityLink == "true">
            <li class="mds-site-navigation__list-item <#if page.name=='CommunityPage'>mds-site-navigation__list-item--active</#if>">
                <div class="mds-site-navigation__list-item-inner">
                <a aria-label="${text.format("general.Community")}" class="mds-button mds-button--large mds-button--flat-no-background mds-site-navigation__button" href="/" role="button">${text.format("general.Community")}</a>
                </div>
            </li>
        </#if>
        <#list tlc as nav>

          <#assign hasChildren = false>
          <#assign boardCount = rest("/categories/id/${nav.id}/boards/nested/count").value!"0" />
          <#assign catCount = rest("/categories/id/${nav.id}/categories/nested/count").value!"0" />
          <#if (boardCount?? && boardCount?number gt 0) || (catCount?? && catCount?number gt 0) >
              <#assign hasChildren = true>
          </#if>
         

          <li class="mds-site-navigation__list-item <#if coreNode.id == nav.id || coreNode.hasAncestor(nav.id)>mds-site-navigation__list-item--active</#if>">
              <div class="mds-site-navigation__list-item-inner">
                  <#if hasChildren>
                      <button class="mds-button mds-button--large mds-button--flat-no-background mds-site-navigation__button" type="button" data-mds-navigation-container-target="site-nav-navigation-container-${nav?index}" role="button">
                          <span class="mds-button__text">
                            <#if (nav.title)??>${nav.title}</#if>    
                          </span>
                          <svg class="mds-icon mds-button__icon mds-button__icon--right" aria-hidden="true">
                              <use xlink:href="/html/assets/mds_icons.svg#caret-down--s"> </use>
                          </svg>
                      </button>
                  <#else>
                      <a class="mds-button mds-button--large mds-button--flat-no-background mds-site-navigation__button" href="${nav.view_href}" role="button"><#if (nav.short_title)??>${nav.short_title}<#else>${nav.title}</#if></a>
                  </#if>
              </div>
              <div id="site-nav-navigation-container-${nav?index}" class="mds-navigation-container mds-container--dark">
                <div class="mds-components-close-dropdown"><button aria-label="${text.format("images.button_dialog_close.alt")}" type="button" role="button" class="mds-button mds-button mds-button--icon-only mds-doc-icon-swatch--small"><svg aria-labelledby="title" class="mds-icon mds-button__icon mds-button__icon--left"><title>remove</title> <use xmlns:xlink="<a href="http😕/www.w3.org/1999/xlink" target="_blank">http😕/www.w3.org/1999/xlink</a>" xlink:href="/html/assets/mds_icons.svg#remove"></use></svg></button></div>
                  <div class="lia-quilt-row">
                    <div class="lia-quilt-column-06">
                      <div class="title"><a href="${nav.view_href}"><#if (nav.short_title)??>${nav.short_title}<#else>${nav.title}</#if></a></div>
                      <div class="description"><a href="${nav.view_href}"><#if (nav.description)??>${nav.description}</#if></a></div>
                    </div>
                    <#assign liql_query2 = "SELECT short_title, title, view_href, id, description FROM boards WHERE depth=2 AND parent_category.id='${nav.id}' AND hidden=false ORDER BY position ASC" />
                    <#assign subBoards = executeLiQLQuery(liql_query2) />
                    <div class="lia-quilt-column-18">
                    <div class="baords-container">
                    <#list subBoards as subboard>
                        <div class="lia-quilt-column-08 boards">
                          <div class="title"><a href="${subboard.view_href}"><#if (subboard.short_title)??>${subboard.short_title}<#else>${subboard.title}</#if></a></div>
                          <div class="description"><#if (subboard.description)??><a aria-label="${subboard.title}" href="${subboard.view_href}">${subboard.description}</a></#if></div>
                        </div>
                    </#list>
                    </div>
                    </div>
                  </div>
              </div>
          </li>
        </#list>
        <#if user.registered>
      	<li>
          <a href="/t5/forums/postpage/board-id/@support" aria-label='${text.format("menubar.create_support_case")}' title='${text.format("menubar.create_support_case")}' class="create-case-btn lia-button lia-button-primary">${text.format("menubar.create_support_case")}</a>
      	</li>
      	</#if>
    </ul>
</nav>
<@liaAddScript>
  ;(function($) {
    $(document).ready(function () {
      $('body').on('click', '.mds-site-navigation .mds-site-navigation__button',function(e) {
        $('.mds-navigation-container').removeClass('mds-navigation-container--visible');
        $('#'+$(this).data("mds-navigation-container-target")).addClass('mds-navigation-container--visible');
        
      });
      $('.mds-components-close-dropdown .mds-button').click(function(){
          $('.mds-navigation-container').removeClass('mds-navigation-container--visible');
      });
    });
  })(LITHIUM.jQuery);
</@liaAddScript>
</@compress>