Hello,
i have added this code in your customizer because your elementor has not included font-awesome css file into it. that is why it was not working.
add_action('wp_head',function(){
?>
<link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet">
<?php
});
here it is :
http://prntscr.com/nkx2hq