font awesome icons invisible in editor

Hi, thanks for the plugin, it’s the best addition to mce I have seen so far!

I can select font awesome icons but they don’t show in the editor. However, they show correctly in the post preview/final. The reason is a GET error for this url: “/wp-content/plugins/best-editor/assets/font-awesome/css/font-awesome.min.css?wp-mce-49110-20201110” that happens only in the editor screen.

This 404 error shows as NS_CORRUPTED_CONTENT in firefox, and type is incorrectly set as html instead of css.

I use autoptimize and Cloudflare, but both are disabled for the admin side of the site. I purged all caches just in case, and disabled Cloudflare caching, but still this 404 error.

the theme is use is newsphere, and it embeds font-awesome 4.7.0. I renamed its included min.css so it cannot load at all, but error persist.

Can you help? Or do you think it’s another plugin?