List of steps to reproduce:

• Create or administer wiki, to add a logo as instructed by the FAQ page.
• Clear cache, etc., and load the main page.
• Observe no logo appearing, confirm using browser dev tool that mw-logo-icon doesn't exists.

What happens?:
The logo doesn't appear on the wiki.
The logo is evidently set correctly, as the file is referenced in the og:image property for OpenGraph links.

What should have happened instead?:
The wiki.miraheze.org site correctly shows a logo, an <img> tag with the class "mw-logo-icon".

Browser information, screenshots and other applicable information:
Tested on multiple browsers (Firefox and Chromium based).