Unnamed Appointments

i am testing eM Client. I have stored my Appointments on an own Owncloud-Server in several calendars (for each family-member one).

I now connected eM Client wird the calenders which worked finde. BUT:

Espeacially in one calender i have now several appointments called (or in german . None of these appointments can be seen in owncloud or thunderbird. Has anyone an idea?

With calender-data i am very sensibel - i am afraid of data loss