I saw this post a few days ago too. I already tried Option 2, didn't work. Options 1, 3, and 4 don't work either as once again I cannot enabled App Notifications and I get a message at the top stating, "Some settings are managed by your organization."
I feel like my question is getting ignored in some aspect. All I need to know is which registry key gets changed when you Windows+R then gpedit.msc go to User Configuration\Administrative Templates\Start Menu and Taskbar\Notifications there would be "turn off toast notifications" enable it then disable, using something like Regshot or Process Monitor. If I knew which key this entry changes, I'm pretty sure I will be able to turn on app notifications. I cannot do this myself as I am running Windows 10 Home, and GPEdit.msc is only included in pro and enterprise versions.