Maybe kind of misunderstanding.
In manual setting, you get the notification, but the List of available Updates is empty. To start the update, you have to toggle to auto, and back to manual. Working, but the logic behind is not intuitive.
My proposal of semi-auto was that after notification this available update is shown in the list (as the only one), and can be selected. No need for toggle of setting.
The manual setting could be used for pure manual installation (without notification), showing multiple entried of possible up-/downgrades in the list.
Auto & off remain unchanged.
This is nothing critical, only a proposal for improvement. CE team may think about to change the logic of this menu to a more intuitive approach.