Good afternoon Mike and welcome back!
Thank you for reaching out to us.
We are sorry to hear about the struggles you had to deal with while trying to add recurring events.
I would love to help you with this topic.
By the looks of it, you are most probably dealing with a recent issue impacting our customers that are using https.
More specifically, if you head over to Settings > General in WP-Admin, you have to make sure that both URLs found there are set to https.

Let me know if that helps.
Have a great day!
Geoff B.