To reproduce:
1. Double click over the scheduler to open the edit dialog.
2. Click the Recurrence button.
3. Check "all day event"
4. Select Yearly recurrence pattern , every January 1st
5. Confirm the appointment.
6. Navigate to the first occurrence, select it and press Delete key. Confirm the deletion.  You will see that the appointment is still visible. However, if you chose the "all day event" from the first edit dialog, everything works as expected.