Hey Benjamin,
Thank you for reaching out to us!
I’m very sorry about this issue you are experiencing.
Can you please make sure that both The Events Calendar and Events Calendar PRO are up to date? After that, please access your Dashboard and head over to Settings -> Permalinks for a permalink flush (no need to change anything, just visit the permalinks page: WordPress will automatically flush your permalinks once you visit it).
Don’t forget to clear your site’s cache and your browser cache after this change.
Let me know if this helps to solve your problem! If the issue persists, can you please share with us the URL where you are experiencing the problem so we can further investigate?
Thanks!
Patricia