Hello,

Our theme supports only Font Awesome 5 sets, and you are using Font Awesome 4 set icons as well, that is why the issue occurs on your site, so we suggest you only use Font Awesome 5 set Icons for better performance of your site.

OR

If you still want to use those icons then try with the below given solution.

You need to add the font library manually in your website. By adding the following script in the header.php file of your child theme. Then you can use all the icons from font awesome 4.

<script src="https://use.fontawesome.com/a9e8be7baf.js"></script>

Best Regards.