Feed caching problem

Hello,

I am using wp super cache and I love it. Thanks a ton for amazing plugin. Btw, I am also using cloudflare flexible ssl with minification of CSS and Java. I am also using a mobile theme for my site.
My expires header in htaccess is as below

# BEGIN Expire headers

<ifModule mod_expires.c>
ExpiresActive On
ExpiresDefault “access plus 5 seconds”
ExpiresByType image/x-icon “access plus 691200 seconds”
ExpiresByType image/jpeg “access plus 691200 seconds”
ExpiresByType image/png “access plus 691200 seconds”
ExpiresByType image/gif “access plus 691200 seconds”
ExpiresByType application/x-shockwave-flash “access plus 691200 seconds”
ExpiresByType text/css “access plus 691200 seconds”
ExpiresByType text/javascript “access plus 691200 seconds”
ExpiresByType application/javascript “access plus 691200 seconds”
ExpiresByType application/x-javascript “access plus 691200 seconds”
ExpiresByType font/truetype “access plus 691200 seconds”
ExpiresByType font/opentype “access plus 691200 seconds”
ExpiresByType application/x-font-woff “access plus 691200 seconds”
ExpiresByType application/x-font-svg “access plus 691200 seconds”
ExpiresByType image/svg+xml “access plus 691200 seconds”
ExpiresByType application/vnd.ms-fontobject “access plus 691200 seconds”
</ifModule>
# END Expire headers

I have a strange problem. My main feed(https://www.mysite.com/feed/) works normally(shows updated lastBuildDate), but my category feeds(https://www.mysite.com/category/latest/feed/) are somewhat deferred/delayed in updating by few days. The delayed feed(lastBuildDate) shows only in desktop but it shows updated feed(lastBuildDate) on mobile. Strange caching problem it looks like… Is there a way to solve it?

Thank you in advance.