Make sure the group cannot be unselected if only one group.
Select "Show All users" if all users are selected

The item was not selected when re-opening the menu.
Keep the logged in user when deselection Show All Users.
Do not unselect group if not selectable.
Synchronize the "Show All users" with user selection.
Merge pull request #2099 from jburel/single-group-selection

Single group selection