Please send your website URL and WordPress admin login details for temporary at [email protected] so we can check and assist you quickly regarding Font Awesome Icons.
I have checked Font Awesome icons in other client’s website which is developed in BuildUp theme and is working fine. So we need to check in your website why it is not showing there.
For that we need WordPress login details of your website for testing purpose.
Please send your login details at [email protected] so we can check and solve this issue quickly.