Good evening Matt and welcome back!
Thank you for reaching out to us.
We are sorry to hear about the events you have created not displaying.
I would love to help you with this topic.
I believe you are on the right track, the message you are getting could absolutely be a reason for that behaviour.
As a first troubleshooting step, could you please provide us with your system information in a private reply ? (following the instructions found in the link)
My other recommendation would be to update the Events Calendar Pro to its latest version (4.1.1) to see if that fixes the issue.
Let me know how that goes.
Best regards,
Geoff B.