我已经向根.htaccess添加了下一个指令：
<IfModule mod_expires.c>
ExpiresActive On
ExpiresDefault "access plus 1 month"
ExpiresByType image/gif "access plus 1 month"
ExpiresByType image/png "access plus 1 month"
ExpiresByType image/jpg "access plus 1 month"
ExpiresByType image/jpeg "access plus 1 month"
ExpiresByType video/ogg "access plus 1 month"
ExpiresByType audio/ogg "access plus 1 month"
ExpiresByType video/mp4 "access plus 1 month"
ExpiresByType video/webm "access plus 1 month"
ExpiresByType text/html "access plus 0 seconds"
ExpiresByType text/cache-manifest "access plus 0 seconds"
ExpiresByType text/xml "access plus 0 seconds"
ExpiresByType application/xml "access plus 0 seconds"
ExpiresByType application/json "access plus 0 seconds"
ExpiresByType application/rss+xml "access plus 1 hour"
ExpiresByType application/atom+xml "access plus 1 hour"
ExpiresByType image/x-icon "access plus 1 week"
ExpiresByType application/x-font-ttf "access plus 1 month"
ExpiresByType font/opentype "access plus 1 month"
ExpiresByType application/x-font-woff "access plus 1 month"
ExpiresByType image/svg+xml "access plus 1 month"
ExpiresByType application/vnd.ms-fontobject "access plus 1 month"
ExpiresByType text/css "access plus 1 year"
ExpiresByType application/javascript "access plus 1 year"
ExpiresByType text/javascript "access plus 1 year"
但是，没有任何效果，所有图像仍未缓存。我看到缓存可以以某种方式工作，因为js和CSS文件被缓存了，但是图像却没有。我已经搜索了网站上的所有htaccess，还检查了.conf文件夹中的所有etc文件，但找不到覆盖该规则的内容。
还有什么会导致这种问题？