For my user account, the Windows Push Notification Platform seems to be messed up. I have the following symptoms:
In the
Settingscharm,Notificationsis grayed out. The tool-tip isTurned off by Group Policy.Visual Studio fails to install an app that is capable of toasts and live tiles with the following error:
Error 1 Error : DEP0700 : Registration of the app failed. error 0x80072EE4: The Visual Elements extension failed while processing the Notification element. (0x80073cf6) MenSaarThe event log
Microsoft/Windows/Microsoft-Windows-AppXDeploymentServer/Operationalcontains many related entries, the most relevant of which appears to be the following:error 0x80073CF6: AppX Deployment operation failed. The specific error text for this failure is: error 0x80072EE4: The Visual Elements extension failed while processing the Notification element.The same app fails to install from the Windows Store.
The event log
Microsoft/Windows/PushNotifications-Platform/Operationalcontains many of the following entries:The Windows Push Notification Platform has encountered an error in file: base\diagnosis\platform\notifications\platform\endpoint\platform.cpp, function NotificationPlatform::Initialize, line 595: 0x80072EE4.The Windows Push Notification Platform has encountered an error in file: base\diagnosis\platform\notifications\platform\ui\cachemanager.cpp, function CacheManager::Initialize, line 170: 0x80072EE4.The event log
Microsoft/Windows/Microsoft-Windows-TWinUI/Operationalcontains many of the following entries:The Windows Notification platform has failed initialization. Notifications will not work until after a restart.My Notifications settings are in the following state:

Usually, this is impossible: The latter options are only grayed out if the first option is disabled. I can un-gray the latter options by disabling and re-enabling the first option, but this does not persist.
These issues are local to my account (at least the first one, I haven't carefully tested all of them).
By resetting that part to the profile to the default profile, I verified that ~\AppData\Local\ is not the (only) cause of the problem.
Windows logs this error to HKCU\Software\Microsoft\Windows\CurrentVersion\ImmersiveShell\TileNotifications\. While writing the registry entry, explorer.exe has the following stack:

How can I reset the Windows Push Notification Platform? What else could I do to remedy this?