I found several issues while working with the new Calendar in M2.

1- Move an event from one calendar to a new calendar.
This just doesn't work. I try to edit the event, change the calendar, press save
but the event is still on the first calendar.

2- Double click on a day ( QuickAdd ) fill some fields and then press "more options". Fill other fields, press save. The appointment never get saved.

Home this helps

Diego B