Assign a Task - Microsoft Outlook

Thanks so much for this response GeoffLCS. I was afraid I'd get this answer...
Actually I loved using the ToDo App, when it was a separate App that combined Outlook tasks, Planner tasks and additional tasks both at the desk or on my mobile.
In fact, I was pretty sure that I'd been able to assign tasks from the ToSo app as well, but may have mixed this up.
Thanks for your tipp to create a shared list - at least there's a "Workaround". 
Is there anything we can do to get Microsoft to re-add the "assign task" feature?