Live Preview not working

Hello,

The Live Preview feature of the plugin is not working when I make modifications. However, if I make the modifications and hit publish, I will then be able to see that the modifications are in fact been done on my website. From that I can conclude that only the live preview feature is not working. When inspecting the page, I can see that there is one error related to the plugin as follows:

Uncaught ReferenceError: egfFontPreviewControls is not defined
at preview.init (http://www.fsrconstruction.com/wp-content/plugins/easy-google-fonts/assets/js/customize-preview.js:55:11)
at http://www.fsrconstruction.com/wp-content/plugins/easy-google-fonts/assets/js/customize-preview.js:710:10
at http://www.fsrconstruction.com/wp-content/plugins/easy-google-fonts/assets/js/customize-preview.js:712:2

When I open customize-preview.js, the following line is marked with an error mark:

_.each( egfFontPreviewControls, function( value, id ) {

Anyone can help me?

Thanks