clicking "Save Recipe" brings up a blank gray box

When the “Save Recipe” button is clicked, it brings up a blank gray box and nothing else. I’m not sure which option I need to change in the plugin settings to correct this (it it is an error) or if someone needs to be logged into ziplist for the button to function properly. Any advice you can give me would be greatly appreciated.

My site is http://www.livebettertogether.org

Thank you!

https://wordpress.org/plugins/ziplist-recipe-plugin/