Setup: DAViCal server on NAS.
CalDAVzap on linux client.
Business Calendar Pro + CalDAVsynch on Samsung Galaxy Note 2 10.1.
Business Calendar Pro + CalDAVsynch on Motorola Moto G.
iPad with standard iPad calendar.
The appointment is a repeating event, to repeat every two weeks.
Starting tomorrow. Ending 2014-12-31. The appointment exists on all
clients. It is displayed in weeks 10, 12, and so on.
Using CalDAVzap I edit the first occurrence of the appointment and
change all occurrences: change the starting date to one week later. It
is now displayed in weeks 11, 13, and so on.
The change is picked up correctly by the iPad.
The Samsung now shows the (new?) appointment in weeks 11, 13, ... but
still shows the (old?) appointment in weeks 10, 12, ...
The Motorola doesn't show either appointment.
Unfortunately I was just a little too late to intercept the log file.
I'l try to be more quick if something like this happens again.