Font awesome icons do display at all. I’ve deactivated and deleted all plugins, switched themes, reset database, and finally reinstalled WP. There are no changes to the functions.php file. No related errors in cPanel, and all caching is turned off. The syntax for Font Awesome can be seen in the source, and the stylesheet rules are there on inspection. Checked with Siteground support for any issues at their end (none).
All sites are the latest version of GP and GPP – why would they all render differently?