Thank you for all of your work on this plugin. I have searched for an answer before writing because I thought it would be simple solution, but I cannot select "disk enhanced' from the drop down menu. This is a multi-site installation but the same thing has occurred on a single site.
I followed the installation steps carefully; no other caching plugins were active, no files in the wp-content and this director was chmod to 777 before I installed the plugin. This is the third time i have gone through this procedure and yes PHP Safe Mode is OFF.
From reinstalling core files to optimizing the database, disabling all other plugins and working with a barebones theme-still I cannot get this option which is recommended to work.
I would appreciate your assistance when you get a moment.