Contact form file upload missing ajax throbber

Not sure if this is the same but after working on bootstrap barrio I realised that I was missing the ajax spinner. Looking at other themes such as claro, it seems they require some js and css for this to work:

For bootstrap it seems to be missing the following in theme.js

    /**
    * Theme override of the ajax progress indicator for full screen.
    *
    * @return {string}
    *   The HTML markup for the throbber.
    */
    ajaxProgressIndicatorFullscreen: function () {
      '<div class="ajax-progress ajax-progress-fullscreen spinner-border glyphicon glyphicon-refresh glyphicon-spin" role="status"><span class="visually-hidden">Loading...</span></div>';
    },

Alternatively the same can be implemented in your sub theme using attach: function (context, settings) { e.g.

      /**
      * Theme override of the ajax progress indicator for full screen.
      *
      * @return {string}
      *   The HTML markup for the throbber.
      */
      Drupal.theme.ajaxProgressIndicatorFullscreen = () =>
        '<div class="ajax-progress ajax-progress-fullscreen spinner-border glyphicon glyphicon-refresh glyphicon-spin" role="status"><span class="visually-hidden">Loading...</span></div>';

then in your theme you will need some css. e.g.:

/* Full screen throbber */
.ajax-progress-fullscreen {
  --bs-glyphicon-spin-font-size: 2rem;
  --bs-glyphicon-spin-color: @gray-darker;
  position: fixed;
  z-index: 1261;
  top: 50vh;
  left: 50vw;
  font-size: 2rem;
  margin-top: calc(--bs-glyphicon-spin-font-size/-2);
  margin-left: calc(--bs-glyphicon-spin-font-size/-2);
}

This is a modified version of whats in web/core/modules/system/css/components/ajax-progress.module.css