Hi Laurent!
I’m sorry you are experiencing that issue 🙁
It seems to be a Javascript issue. Could you please check if there are any console errors by inspecting the page? Here’s a guide on how to do that > https://theeventscalendar.com/knowledgebase/using-google-chrome-developer-tools/ If there are any, please send me a screenshot of it so we can take a look.
If there are no console errors, it could be related to a theme or plugin conflict, so could you please go through the complete Testing for Conflicts guide and let me know what you find in the process?
I know it’s a production site so you might not want to be making changes. If this is the case, then you should see if you can test it in a dev / staging site.
Let me know how that goes.
Thanks!
Victor