Hello James,
I checked your given site URL it seems that you have added the custom CSS code for the icon in the child theme, I would suggest you please find this custom CSS code from your child theme style.css.
.x-navbar .desktop .x-nav li > a > span::after {
content: "\f078" !important;
font-size: 70% !important;
}
Now you need to replace the above custom CSS code with the given code.
Updated Custom CSS code
.x-navbar .desktop .x-nav li > a > span::after {
content: "\f078" !important;
font-size: 70% !important;
font-family: FontAwesome;
}
The purpose of providing custom CSS is to show you how to add CSS code to your site. Writing custom CSS is outside the scope of our theme support. If you need more customization, you need to learn CSS and learn how to use the browser’s element inspector.In case you have no idea about coding you can subscribe to One where customization questions are answered.
Hope it helps.
Thanks