KOrganizer Calendar Data Location : iCal Calendar Folder : empty

When I create a new calendar with the option iCal Calendar Folder, the folder stay empty.

Settings > Configure KOrganizer > Calendars > Add > iCal Calendar Folder
I select a Directory
(select the directory whose contents should be represented by this ressource)
(il the directory does not exist, il will be created)
‘read only’ box not checked

I create a new event in the new calendar
update folder
update calendar
Quit KOrganizer

The folder stay empty, data is not stored there.

when i open KOrganizer again, i can see my new calendar with my new event

debian bookworm
KOrganizer 5.22.3 (22.12.3)
KDE Frameworks 5.103.0
Qt 5.15.8