Hey Matthew,
Thank you for reaching out to us!
I’m sorry to hear that you are experiencing this issue, that’s odd! Could you please make sure that all plugins (specially The Events Calendar and Events Calendar PRO) are up-to-date? When did you notice that this problem started? Was it recently?
Also, can you identify any pattern in these exclusions? As I can see in the screenshot you shared, the exclusions are all from 2016: perhaps deleting old recurring events would help you to prevent this error. Under Events > Settings > General Settings I would recommend you to adjust the “Create recurring events in advance for” and “Clean up recurring events after” to smaller numbers.
I hope this helps you get started! Let me know your answer to these questions so we can further investigate your case.
Thanks!
Patricia