This works for me. You will need to provide more information. What's in your config.runtime.php? Have you pulled the latest code from github? Have you made any modifications? This sounds like the problem fixed by https://github.com/phpBBSEO/usu/issues/63 where the "FIX RELATIVE PATHS" change to .htaccess was not included (as a result, it does not find images).
This works for me. You will need to provide more information. What's in your config.runtime.php? Have you pulled the latest code from github? Have you made any modifications? This sounds like the problem fixed by https://github.com/phpBBSEO/usu/issues/63 where the "FIX RELATIVE PATHS" change to .htaccess was not included (as a result, it does not find images).