How to get calendar and to-do reminders as set?

After KDE Plasma update from 5.19 to 5.22.3 (on desktop PC – openSuse Leap 15.5) and to 6.0.2 (on Notebook – openSuse Tumbleweed) the reminder does not work correctly. That means, I do not get the reminder sound as set in reminder tab of the related event (KOrganizer), instead I only hear a short quiet beep while a little box appears over the control bar. And when I click on this box, this do not open any more the event edit box as usually happened in the old version.
The same behaviour for to-do items.

How can I get reminded to events and to-does in similar manner as I have set or, what is the same, as done in the previous KDE Plasma version?