Async Java disabling Featurebox

Hi there! Awesome plugin. I saw a noticeable increase in site speed, so I’ll definitely be spreading the word. The only issue is that if I load js asynchronously, the opt-in form for my feature box doesn’t work. You can still type in your email address, but if you click the CTA button nothing happens. It also messes up the formatting on my sidebar form and search bar a little bit. Any help would be greatly appreciated. Thanks! https://wordpress.org/plugins/async-js-and-css/ Here’s my website: http://copytactics.com