Font Awesome Issue

Hi.
I have installed the plugin to replace another one that has been causing some issues.
All set up fine, with one exception – that being that the font awesome image for Twitter-X does not work.
<i class="fa-brands fa-x-twitter"></i>
The same icon works elsewhere on the site, but the Maintenance Page refuses to show it.
Other fa social icons do show on the page, so I’m a bit baffled!

Any suggestions?