This isn’t a theme vs. plugin issue. It is a plugin vs. plugin issue. Event Manager is a plugin, as is WP SEO Structured Data Schema. I have looked at that article and tried to determine if that was the issue. It isn’t.
This is confirmed that WP SEO Structured Data Schema v2.2 is the issue. I deactivated the plugin, and was able to create the event.
I also emailed the developer of the WP SEO Structured Data Schema plugin and directed him to this post in the hopes that everyone could work together to get this issue resolved.
This reply was modified 7 years ago by vader7071. Reason: added additional info