[Hummingbird] Configure Script Deferring - Minification

Im trying to improve my performance test by running "configure script deferring" on a multisite network dashboard. However I get the message: "Please, activate minification first. A new menu will appear in every site on your Network." Im not sure how to activate this as I am not seeing the new menu on the sub-sites. I have activated to host my files on the WPMU DEV CDN.