Accordeon Menu in Eria Template

[bully]

On a almost clean install, Elxis 4.6 and Eria, I am not getting the vertical Accordeon Menu to work proper.
Partially, it will just short open, then immediately close again.

Error in FF/Chrome: TypeError: jQuery.colorbox is undefined.. the debug link: https://it-bizz.net/products-services/:35:3

<script type="text/javascript">
      jQuery(document).ready(function() {jQuery('#user1 .module, #user2 .module, #user3 .module, #user4 .module').matchHeight();});
      function mySidebar() {$('.ui.sidebar').sidebar('toggle');}
      jQuery(document).ready(function($){$('#nav-w').prepend('<a id="menu-icon">Menu</a>');$("#menu-icon").on("click", function(){$("#nav").slideToggle(500,"linear");$(this).toggleClass("active");});});
      jQuery.colorbox.settings.maxWidth  = "95%";jQuery.colorbox.settings.maxHeight  = "95%";
      jQuery(window).bind("resize load",function(){if( jQuery(this).width() > 799 ){jQuery("#nav ul.elx_menu").addClass("sf-js-enabled"); jQuery("#nav ul.elx_menu").superfish({ pathLevels   : 4,delay      : 300,animation   : {opacity:"show",height:"show",width:"hide"},speed      : "fast",});} else { jQuery("#nav ul.elx_menu").removeClass("sf-js-enabled");  }});
   </script>

This is a top level menu item and has child items.

- item I
- Item II
-- Item II-I
-- Item II-II
-- Item II-III
- Item III

I have noticed that also already before, on sub menu, it is always somehow a dodgy.
Currently, I have the template in development, but it's also with a clean original and ALL unmodified files from Elxis 4.6, so I assume, the error is out of the box.

Anyone know, how to fix/handle that?
In fact, the vertical menu is the reason for THIS template.
I have found endless search results to the same error and with them endless proposed fixes. I just don't have a clue, where or how to apply


Thx @ lot
bully

[bully]

 
Replying to myself.
Sorted, somehow for myself....
The link(s) in question where a category link and the child(s) where the single pages

[webgift]

This is really important as we can figure out the issues by ourselves! Bravo!