Add Additional Guests Not Working

Greetings,
I have the latest version installed… with Open Registration option turned on, the green + icon on the RSVP form for adding additional guests is not working, it’s just not clickable. I’ve tried removing all the javascript from the custom theme and still not working. I’ve also tried turning Open Registration off and still not clickable. Please help and thank you so much for the awesome plugin!!!
-Y

https://www.ads-software.com/plugins/rsvp/