Meanwhile, I did some testing on iCal iMac (10.7.5 but apparently everybody else up to El Capitan is left with this bug) by double clicking in a given day > enter title of the event > double clicking the event > edited for all tests the same values like recurrence and 'message with sound'
- NO PROBLEM when entering a new event WITHOUT CHANGING the DEFAULT CALENDAR; tested several times; even if default calendar is SAME or DIFFERENT from the one on iCloud or other iOS devices
- FAILED when creating a new IDENTICAL EVENT BUT CHANGED to a NON-DEFAULT CALENDAR; this failed on each test! Also with or without prior synching iCal, Time Zone support turned on, etc.
- changing the default calendar in iCloud did NOT changed these results; on each occasion where a new event was changed to a non-default calendar, the fault occurs
Remark:
After entering or editing an event, one can remark on top of the screen (iCal 5.0.3) next to the '+'-button the indication 'Updating...' (or something similar; I use the Dutch version where it states 'bijwerken…' MOMENTARILY appearing TWICE. When you try to quickly REOPEN AND BEFORE this 'UPDATING' appears, a 'virgin' event which was edited a first time (switching to a non-default calendar to induce the fault - reversion to previous values of the virgin event), one can see in the event-edit-window MOMENTARILY the CORRECT VALUES reverting to the faulty 'virgin' values. As already expected, the fault (bug) lies in the synching process.
Thank you all who are trying to help each other through this platform, something which should be solely the responsibility of Apple itself.