Appointments+ Confirmed booking, but empty reservation details

I updated to the newest version of Appointments+ have had a week ago. Since that i have had a couple confirmed bookings with every field missing the information of the booker and the date is 1.1.1970. The log shows the email has been sent to:

"Dear ,

We are pleased to confirm your appointment for EXITE Live Games.

Here are the appointment details:
Room: Not defined
01.01.1970 00:00"

What could be the problem?