Icons appearing as boxes

We’ve recently noticed that the fa and sl icons we’re using in the iconbox are appearing as boxes on web, and as unrelated icons on mobile. As an example, we have sl-magic-wand selected in the theme and it appears as a box online and as a surfer on mobile. These used to work fine, but suddenly stopped.

Our theme is up to date, and we’ve tried turning off all of our plugins, but we can’t get it to work anymore. Would love some help in trying to troubleshoot what the issue is!

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