Shared Tasks have no CalDAV URL
A shared task folder cannot be managed via a mail program like Evolution or Thunderbird, because no CalDAV URL is provided for a shared task folder. This means that the guidelines provided here do not work for shared tasks.
CalDAV URLs are available for both personal and shared calendars and for personal task folders. However it is not currently possible to run a shared task list without the web portal.
Is there a way to fix this?