Cannot get Plugin to work

I am a little confused about how the plugin interacts with the wordpress Codex.

<?php

if ( is_active_sidebar( 'header-widget' ) ) : ?>
<div class="container-fluid ypbg banner">
  <div class="row justify-content-center">
    <div class="container">
      <div class="row justify-content-center">
        <div class="col-12 py-3 small text-center">
          <?php dynamic_sidebar( 'header-widget' ); ?>
        </div>
      </div>
    </div>
  </div>
</div>
<?php endif; ?>

This is my code for dislaying the widget. It works fine on its own.
Once I enable the plugin it disappears from all pages.

I cannot share admin access to the site.

Any insight? Am I use the wrong output for the widget?

• This topic was modified 4 years ago by Yui. Reason: please use CODE button for code formatting