[eo_fullcalendar] stuck on 'Loading"

Looking for a simple calendar in my test WP site and all i get is loading when i added [eo_fullcalendar] to a page.

Here it is:

https://n4ser-1.org.n4ser.org/Calendar/

Any ideas??
Thanks
Den

https://www.ads-software.com/plugins/event-organiser/