When you update a recurring calendar event (say, a yearly commemoration date) then you have a selection, to update only the current event or all events with the same rule of repetition (radio buttons).
If you check the latter, none gets updated. Not even the current one.
Oh, there are so many bugs in the calendar feature...
Thanks
hman
The calendar feature needs a deeper investigation and it has been done a lot of development around versions 21 LTS and 24 (trunk, future LTS).
This and possible further calendar bugs have to be reviewed, discussed and fixed in a broader context.
Regards,
Torsten