Hi Pim
I took a look at your site and found this Javascript error: “You have included the Google Maps API multiple times on this page. This may cause unexpected errors.”
Using Your Browser to Diagnose JavaScript Errors
Do you have the Google Maps API key added in other plugins or in your theme settings?
Can you also go through Testing for Conflicts Guide https://theeventscalendar.com/knowledgebase/testing-for-conflicts/ to be sure where the conflict might be.
Please let me know if the issue still persists after these tests.
Thanks
Courtney 🙂