Font Awesome not working with CSS

Hi,

This is an issue that appeared with a theme update. I have a font awesome icon added with CSS and now it doesn’t work anymore.

I used to have this code and it worked, but now it creates only a square:

li.menu-item-language-current>a>span.wpml-ls-native:before {
    content: "\f27b";
    padding-right: 6px;
    font-family: "FontAwesome";
}

Yesterday I looked into it and found another icon that worked for a while, but now I’m back to a square. I even tried the new Load full FontAweseome library option, but it didn’t make a difference. Here’s my current code. How should I make this work ?

li.menu-item-language-current>a>span.wpml-ls-native:before {
    content: '\f4ad';
    padding-right: 6px;
    font-family: "Font Awesome 5 Free"; /* This is the correct font-family*/
    font-weight: 400; 
}

Thanks for your help.

Cheers,

Marc