Font Awesome: Some icons not showing on mobile (iPhone iOS)


I’ve upgraded to the new Font Awesome 5 because I had some trouble displaying some icons (ie Twitter Square and Facebook Square) on mobile devices. By upgrading I hoped to solve the problem, yet it didn’t.

I’ve upgraded to 5 and I’ve tried a lot to see what could be the problem. Even on JSBin the icon shows up on my computer, but not on my mobile device. I have an iPhone running iOS 11.2.

This is the JSBin link where I tried to test it and reproduce the problem. I think the problem is within the Font Awesome source as I can’t narrow it further much down I guess…,output

This is the code from the jsbin:

        <title>Font Awesome Test</title>
        <link href="" rel="stylesheet">
        <p>This is the icon: </p>
        <a href=''><i class="fab fa-twitter-square fa-3x"></i></a>

Anyone familiair with Font Awesome and knows how to solve this?
Note: not all icons are not working. The envelope square icon for example works fine.

<i class="fas fa-envelope-square fa-3x"></i>

Thanks in advance.

EDIT: I have tried to download the icons to my server and link them directly to see if that solved the problem but unfortunately not.