Hey Nick,
Do you have a page with the same title/slug as what you’ve set for ‘Events URL slug‘ under Events > Settings > General? If so, go ahead and delete that page. If not, then disregard that step.
If you haven’t already, please review our Testing for conflicts guide and let me know whether the issue still occurs. I’d also recommend checking out our New User Primer. It’s a useful article that can help answer some general questions you might have.
Also, welcome to the forums! Thank you for posting and have an enjoyable rest of your day.
Cheers!