Some event pages don't work anymore

Hi Jeroen,

Hopefully you can help us. We noticed that some of the events in our list did not work anymore. When we try to edit the page it does give us the edited page with all the content, but when we try to look at it like our visitors would the URL jumps from the original specified URL to something like this: http://domain.nl/wp_theatre_event/292/
And we see an empty page with just our header, footer and menu.

Any ideas on how to fix this?

Thank you!

Scarlet

https://wordpress.org/plugins/theatre/