The main icons missing are:

<i class="fas fa-chevron-down nav-item-caret"</i> from the main menu in the header
<i class="fas fa-arrow-alt-circle-up"></i> from the Back to Top
<span class="icon-calendar" aria-hidden="true"></span> from a Component called JomHoliday

These from the Joomla article info
<i class="far fa-clock"></i>
<i class="far fa-calendar-alt"></i>
<i class="far fa-eye"></i>

And these from the footer module
<i class="fas fa-map-marker-alt"></i>
<i class="fas fa-phone-square"></i>
<i class="fas fa-envelope-open"></i>
<i class="far fa-clock"></i>
<i class="fab fa-facebook-square fa-2x" style="padding-right: 10px;"></i>
<i class="fab fa-instagram fa-2x" style="padding-right: 10px;"></i>
<i class="fab fa-pinterest-square fa-2x" style="padding-right: 10px;"></i>
<i class="fab fa-facebook-messenger fa-2x" style="padding-right: 10px;"></i>

The issue is now solved. It was a conflict with the JCH Optimize component. It was loading out of date cache files for the css. Thank you for your support on this.