Hustle colour customiser

The colour customiser options do not work. The interface does not seem to load properly so I cannot select override colours. Only the 'Pop-up overlay' colour selector works!

There are no console errors when I load the page. I have tried disabling all non-essential plugins temporarily, which didn't help. I tried switching theme to a basic built-in theme and that didn't help.

http://farragobooks.com/wp-admin/admin.php?page=inc_optin&optin=1&tab=design