That option for me is already enabled.
I have tried disabling it and re-enabling it multiple different ways:
Disabled option closed advanced setup, opened advanced setup and re-enabled option.
No effect.
Disabled option, closed advanced setup, restarted windows, opened advanced setup and re-enabled option.
No effect.
Disabled option, closed advanced setup, restarted windows, opened advanced setup and re-enabled option, closed advanced setup, restarted windows.
No effect.
When I accidentally disabled notifications, it was from one of the notification windows that would pop-up.
Where there is an x at the top far right to close that window.
Then to the left of that is a downward facing arrow, when you click on it you are given options:
Manage notifications
Close all notifications
Disable notifications
That is where I accidentally disabled notifications, if that makes any difference.