Stackable menu not working with right menu - Semantic UI

What I'm trying to do is the following:

<stackable menu>
  <item1>
  <right menu>
    <item2>
    <item3>
  </right menu>
</stackable menu>

The output is good on computer, and stacks well on mobile - however item3 is not visible. If I add item4,5...n they are hidden as well.

Am I doing something wrong here, or it's a bug?

Thanks in advance!

It seems there is an open issue here. Try the following:

<link href="https://cdnjs.cloudflare.com/ajax/libs/semantic-ui/2.2.4/semantic.min.css" rel="stylesheet"/>
<div class="ui stackable menu">
    <a class="item">My first left item</a> 
    <a class="item">My second left item</a>
    <a class="right item">My first right item</a> 
    <a class="item">My second right item</a> 
</div>