Displaying search icon instead of Title

On the develop site for a project I’m working on, we have the magnifier icon replaced with the word “GO” to perform the search. I’ve been unable to replicate this in the production environment.

Develop site I’m getting this: (correct)
<input type="submit" value="GO" class="is-search-submit">

On production I’m getting the following code generated: (wrong)

<button type="submit" class="is-search-submit" value="GO">
  <span class="is-screen-reader-text">Search Button</span><span class="is-search-icon">
     (SVG goes here but I think it was causing issues. 
  </span>
</button>

I found this post in the documentation: https://ivorysearch.com/docs/display-text-instead-of-menu-search-icon/
Unfortunately, it doesn’t resolve the issue in our Production Environment.