[Plugin: W3 Total Cache] https rewrite rules problem

Hope someone can help with this problem:
My entire site is https and i’m using mfunc in every page.
I turn on page cache (basic), first load is fine (i can see cache file being created on disk, but debug info shows:

Cache key:      w3tc_mydomain.com_1_page_05f935faf9590a8e30d6249707373a77_ssl
Caching:            enabled
Status:             not cached

On second load I get 500 internal error, same goes for every page…

These are the .htaccess rules:

# BEGIN W3TC Page Cache core
<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteBase /
    RewriteRule ^(.*\/)?w3tc_rewrite_test$ $1?w3tc_rewrite_test=1 [L]
    RewriteCond %{HTTP_USER_AGENT} (240x320|2\.0\ mmp|\bppc\b|alcatel|amoi|asus|au\-mic|audiovox|avantgo|benq|bird|blackberry|blazer|cdm|cellphone|danger|ddipocket|docomo|dopod|elaine/3\.0|ericsson|eudoraweb|fly|haier|hiptop|hp\.ipaq|htc|huawei|i\-mobile|iemobile|j\-phone|kddi|konka|kwc|kyocera/wx310k|lenovo|lg|lg/u990|lge\ vx|midp|midp\-2\.0|mmef20|mmp|mobilephone|mot\-v|motorola|netfront|newgen|newt|nintendo\ ds|nintendo\ wii|nitro|nokia|novarra|o2|openweb|opera\ mobi|opera\.mobi|palm|panasonic|pantech|pdxgw|pg|philips|phone|playstation\ portable|portalmmm|proxinet|psp|qtek|sagem|samsung|sanyo|sch|sec|sendo|sgh|sharp|sharp\-tq\-gx10|small|smartphone|softbank|sonyericsson|sph|symbian|symbian\ os|symbianos|toshiba|treo|ts21i\-10|up\.browser|up\.link|uts|vertu|vodafone|wap|willcome|windows\ ce|windows\.ce|winwap|xda|zte) [NC]
    RewriteRule .* - [E=W3TC_UA:_low]
    RewriteCond %{HTTPS} =on
    RewriteRule .* - [E=W3TC_SSL:_ssl]
    RewriteCond %{SERVER_PORT} =443
    RewriteRule .* - [E=W3TC_SSL:_ssl]
    RewriteCond %{REQUEST_METHOD} !=POST
    RewriteCond %{QUERY_STRING} =""
    RewriteCond %{HTTP_HOST} =mydomain.com
    RewriteCond %{REQUEST_URI} \/$ [OR]
    RewriteCond %{REQUEST_URI} (sitemap\.xml(\.gz)?) [NC]
    RewriteCond %{REQUEST_URI} !(\/wp-admin\/|\/xmlrpc.php|\/wp-(app|cron|login|register|mail)\.php|wp-.*\.php|index\.php|template-shop.php) [NC,OR]
    RewriteCond %{REQUEST_URI} (wp\-comments\-popup\.php|wp\-links\-opml\.php|wp\-locations\.php) [NC]
    RewriteCond %{HTTP_COOKIE} !(comment_author|wp\-postpass) [NC]
    RewriteCond %{HTTP_USER_AGENT} !(W3\ Total\ Cache/0\.9\.2\.5b) [NC]
    RewriteCond "%{DOCUMENT_ROOT}/wp-content/w3tc/pgcache/%{REQUEST_URI}/_index%{ENV:W3TC_UA}%{ENV:W3TC_REF}%{ENV:W3TC_SSL}.html%{ENV:W3TC_ENC}" -f
    RewriteRule .* "/wp-content/w3tc/pgcache/%{REQUEST_URI}/_index%{ENV:W3TC_UA}%{ENV:W3TC_REF}%{ENV:W3TC_SSL}.html%{ENV:W3TC_ENC}" [L]
    RewriteCond %{REQUEST_METHOD} !=POST
    RewriteCond %{QUERY_STRING} =""
    RewriteCond %{HTTP_HOST} =mydomain.com
    RewriteCond %{REQUEST_URI} \/$ [OR]
    RewriteCond %{REQUEST_URI} (sitemap\.xml(\.gz)?) [NC]
    RewriteCond %{REQUEST_URI} !(\/wp-admin\/|\/xmlrpc.php|\/wp-(app|cron|login|register|mail)\.php|wp-.*\.php|index\.php|template-shop.php) [NC,OR]
    RewriteCond %{REQUEST_URI} (wp\-comments\-popup\.php|wp\-links\-opml\.php|wp\-locations\.php) [NC]
    RewriteCond %{HTTP_COOKIE} !(comment_author|wp\-postpass) [NC]
    RewriteCond %{HTTP_USER_AGENT} !(W3\ Total\ Cache/0\.9\.2\.5b) [NC]
    RewriteCond "%{DOCUMENT_ROOT}/wp-content/w3tc/pgcache/%{REQUEST_URI}/_index%{ENV:W3TC_UA}%{ENV:W3TC_REF}%{ENV:W3TC_SSL}.xml%{ENV:W3TC_ENC}" -f
    RewriteRule .* "/wp-content/w3tc/pgcache/%{REQUEST_URI}/_index%{ENV:W3TC_UA}%{ENV:W3TC_REF}%{ENV:W3TC_SSL}.xml%{ENV:W3TC_ENC}" [L]
</IfModule>
# END W3TC Page Cache core

Thanks

https://www.ads-software.com/extend/plugins/w3-total-cache/