Hi Christoph!
I’m sorry you experienced that issue.
We’ve had some other users reporting the same problem and we are already investigating it. It seems to have been a glitch with the Facebook API that we can’t reproduce at the moment, so could you please try making the connection with Facebook again and see if it works?
If it doesn’t, please go to your wp-admin > Events > Help and send us a screenshot of the Event Aggregator System Status.
Let us know how it goes.
Thanks,
Victor