Why some font-awesome icons are not rendered

In my laravel 5.7 / Bootstrap 4.1 app I installed font-awesome package with command

npm install font-awesome --save

and in my package.json I have :

"dependencies": {
    ... 
    "font-awesome": "^4.7.0",
    ... 
}

In webpack.mix.js there is line :

mix.copy('node_modules/font-awesome/fonts', 'public/fonts');

In fonts directory I see

nick@nick:project/public/fonts$ ls -la
total 1080
drwxrwxrwx 1 root root   4096 лис  9 14:32 .
drwxrwxrwx 1 root root   4096 лис  6 06:04 ..
-rwxrwxrwx 1 root root 134808 лис  9 14:32 FontAwesome.otf
-rwxrwxrwx 1 root root 165742 лис  9 14:32 fontawesome-webfont.eot
-rwxrwxrwx 1 root root 444379 лис  9 14:32 fontawesome-webfont.svg
-rwxrwxrwx 1 root root 165548 лис  9 14:32 fontawesome-webfont.ttf
-rwxrwxrwx 1 root root  98024 лис  9 14:32 fontawesome-webfont.woff
-rwxrwxrwx 1 root root  77160 лис  9 14:32 fontawesome-webfont.woff2
drwxrwxrwx 1 root root   4096 лис  7 10:16 roboto
drwxrwxrwx 1 root root      0 лип 22 08:07 vendor

The problem is when I try to use these icons, not all of them are rendered. Say icons fa fa-alicorn or fa fa-air-freshener are empty. I select icon from this https://fontawesome.com/icons?d=gallery&q=freshener selector.

You can check it by http://votes.nilov-sergey-demo-apps.tk/admin/dashboard url, under "Icons Samples" block there some some icons which are visible, but some not.

Why? Are these different version of icons in my app?

Thanks!

via Chebli Mohamed