Why i cant use “itemListElement” to as attribute?

Here is my code from textarea field of Page section in plugin settings

<li itemprop="itemListElement" itemscope itemtype="https://schema.org/ListItem">
  <a itemprop="item" title="%title%" href="%link%" class="%type%" bcn-aria-current>
    <span itemprop="name">%htitle%</span>
  </a>
  <meta itemprop="position" content="%position%">
</li>

When i try save changes after page reload <li> elements have no itemprop, itemscope and itemtype attributes. They disappear.

<li>
  <a itemprop="item" title="%title%" href="%link%" class="%type%" bcn-aria-current>
    <span itemprop="name">%htitle%</span>
  </a>
  <meta itemprop="position" content="%position%">
</li>

Why it can’t be used as I need?