@sLaNGjI's
Also, in the part
#
# Skip WordPress 404 Error for Static Files
#
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} \.(php|css|js|htc|html|htm|rtf|rtx|svg|svgz|txt|xsd|xsl|xml|asf|asx|wax|wmv|wmx|avi|bmp|class|divx|doc|docx|eot|exe|gif|gz|gzip|ico|jpg|jpeg|jpe|mdb|mid|midi|mov|qt|mp3|m4a|mp4|m4v|mpeg|mpg|mpe|mpp|otf|odb|odc|odf|odg|odp|ods|odt|ogg|pdf|png|pot|pps|ppt|pptx|ra|ram|svg|svgz|swf|tar|tif|tiff|ttf|ttc|wav|wma|wri|xla|xls|xlsx|xlt|xlw|zip)$ [NC]
RewriteRule .* - [L]
#it seems that including xsd|xsl|xml| in the above directive interferes with Yoast Wordpress SEO sitemaps (gives 404)..
Removing xsd|xsl|xml| and keeping the rest as it is fixes it!