Events not listed in dashboard

Wordpress Version: 4.9.4
Plugin Event Organisor Version: 3.6.3

Since a few days the Event Organiser in the backend doesn’t show me any event…
On the frontend there is everything ok,

Publishing a new Event also doesn’t work correctly. The fields Start/End Date/Time now have no more dropdown-list and also the Location-field has a problem. In the field Loacation there is just this text: “Einen \t\t\t\tVeranstaltungsort \t\t\t auswählen. If i click on it, i got no dropdown list…

If i click on the categories, i got the following:

Please help me.

The page I need help with: [log in to see the link]