Hi Jeremy,
We are able to verify that the issue does not occur with:
2017 theme
The Events Calendar Version 4.6.21
The Events Calendar Pro Version 4.4.30
If we then activate Yoast SEO Version 7.9.1 (or Yoast 7.9.0), the issue fatal error from Events Calendar Pro then occurs. It would appear there is some sort of conflict between Yoast SEO and Events Calendar Pro plugins.
Since this doesn’t occur in Events Calendar Pro 4.4.29.2 it would seem something changed?
Bill