Events not displayed in Frontend

I have created several events in the Admin Calender View. (incl. all data like name, date and event type)

The events are not visible in the frontend calender view.

When I go to the Admin Event List View, I can see the event. When I open it with ‘edit’, the field for ‘Event type’ is NOT populated anymore. After setting the right value in this view and save the event again, it is also visible in the frontend