Thank you for the info about Toolset. I’ll look into this and see if we can find what the issue may be.
The theme does not load the FontAwesome 5.0 library.
It is bundled with FontAwesome 4.7 so the correct html to use would be <i class="fa fa-xxxxx"></i> and not ‘far’ or ‘fas’. It won’t work if you attempt to mix the two by using a 5.0 icon with the 4.7 code.