Hello, @GazTheGoat,
First of all, you have to go to XStore >> Theme Settings >> Speed Optimization and turn ON FontAwesome Support: https://postimg.cc/620fQTCy and then you have to copy the name of the FontAwesome Icon from the FontAwesome site: https://postimg.cc/qNynRzT4 and paste it in the Menu Settings: https://postimg.cc/0r4J0p59
It will surely work for you, as it is working for me on my test site: https://postimg.cc/B8hvQ0XJ
And an important Note: Please try to use the FontAwesome version 5, https://postimg.cc/3k18nTj2 the icon you were trying to use is from the FontAwesome version 6 and that was the main reason for the issue: https://postimg.cc/KRymbzJn
Hope this helps and all is clear now.
Regards 8Themes Team.
