Tasks are not properly killed and remain in the "Terminate Task" list forever

If I start a task via the Task list on the right, and then try to terminate it with the "Terminate Tasks" menu item, nothing happens and the task remains running and in the list of tasks forever.

If I try to re-run the task again, I get the "The task is already running active" with options to "Terminate Task" or "Restart Task". If I "Terminate Task", nothing happens. If I "Restart Task", a new task is run but since the previous task is still active, I get port conflicts and the task fails.