Good evening Oliver and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
We are sorry to hear about the plugin conflict you have experienced.
I would love to help you with this topic.
The simplest solution to this issue would be to update Visual composer to the current version (5.2). The more complicated solution would be to downgrade all of your plugins and WordPress to versions that were released around April 2016.
Let me know if that helps.
Have a great day!
Geoff B.