ImageChecker fails d/t staged state of AppX pkgs, but no staged AppX found

So, ended up figuring this out with some effort:

1. Some Windows features were uninstalled in an effort to streamline the resulting images/bloat, but this caused those AppX packages to be marked as staged instead of installed. They cannot be removed (or not easily, and should not). They did not show up as staged in the cmdlets that are in the AWS tips section for this. In order to reveal these, the following code needs to be executed:

Get-AppxPackage -AllUsers | Format-List -Property PackageFullName,PackageUserInformation

(see this Microsoft article for a full explanation of the problem and how to check: https://docs.microsoft.com/en-US/troubleshoot/windows-client/deployment/sysprep-fails-remove-or-update-store-apps)

2. Once the packages in question are identified, I did actually try to uninstall them, but due to ownership by the system 'nt authority\system' it is not really possible to do so (or appears so without things getting rather messy). The solution was to simply change the status from Staged to Installed by forcing their install to the user. For instance, to just cycle through the entire AppX list and install any listed packages that are not already in the Installed state:

Get-AppxPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}

Kudos to this article on how to do so: https://www.howtogeek.com/224798/how-to-uninstall-windows-10s-built-in-apps-and-how-to-reinstall-them/