[Plugin: WordPress SEO by Yoast] W3TC caching not working when updating to WP SEO 1.2.8.1

When I updated the plug-in to version 1.2.8.1, the w3tc caching mechanism stopped functioning correctly. While viewing the page, the w3tc comment is shown in the footer of the page but not saved in w3tc/pgcache and minified folder.

For the time being I have reverted to version 1.27.

Thanks

http://wordpress.org/extend/plugins/wordpress-seo/