When I right-click a DAV calendar folder in the sidebar of Korganizer and select "Update Calendar Folder" nothing happens, i.e., the calendar is not updated. 

When I right-click the calendar itself and select "Update Calendar" it works. Also refreshing the calendar from akonadiconsole works as expected. 

I am therefore unsure if this is a bug of Korganizer or the DAV Resource. 

If the update of a single folder is unsupported by the resource it should update the complete resource instead.