With the latest two 12.x versions of US with PHP 7.x, the Genesis child theme Dynamik Website Builder fails to activate. Works fine on all previous US versions without PHP 7.x.
One of the more adept members on the DWB Forum tracked it down to adding the following to the httpd.conf file:
Restart Apache after adding this to the end of the file allows DWB to activate and work normally.
Perhaps this could be added to the next version of US