I’ve narrowed it down to an incompatibility with W3 Total Cache.
What’s weird is that usually there’s only compatibility issues with plugins when CSS and JS minification is enabled. On this site I only had HTML minification enabled, but there was still the issue.
Yes, everything is updated and current. The events/ticket plugins are brand new installs, and I updated WP to the latest prior to the installation of the event/ticket plugins.
Do you have any specific insights other than a default template reply?