RSVP "Add to Calendar" button not working

kandg2020

I have had a couple guests say that once they get through the RSVP process that they have the option to click "add to calendar" and when they do an error message pops up.  Any suggestions?

knottie86d0ce6603b9977c

I too get an error that reads: {"error":"event time was zero"}
Help! How do we fix this?