Customization won´t work under Wordpress 4.9.1

be carefull to update your WP 4.9 to 4.9.1.
the plugin won´t work under 4.9.1 so far.
if you have updated your wp you can download the version 4.9 here: https://wordpress.org/download/release-archive/

or you can download the plugin WP Downgrade to get the WP 4.9

Cheers