When I edit an instance of a recurring event, it detaches it from the schedule. Great. When I edit the recurring event later, the missing instance is recreated and I now have two events on that date. the detached one and the recurring one.

The sytem should remember when an event has been detached and not recreate the missing instance each time the recurring event is edited.

Secondly, when I want to delete only an instance of a recurring event, all instances are deleted. This is not the expected behaviour. I figured out, if I detach the instance and then delete it, it works. But that is quite cumbersome to only delete one instance. Maybe a popup box asking me to delete either the instance or the whole recurrence would solve this issue.