PackageManager "Staging" call for App Attach fails with ACCESS DENIED if made from inside a container.

[TimMangan]

Describe the bug

As originally reported as MicrosoftDocs/winrt-api#2436 (comment) which was rejected as a product but rather than a documentation bug, you cannot write a modern application that runs inside a MXIS container to manage App Attach packages. We want our management apps to also be written as modern apps, right?

The "staging" option of PackageManager that is required for AppAttach like deployment works just find in an unpackaged traditional application, but the same code fails when inside an MSIX package.

See original report MicrosoftDocs/winrt-api#2436 (comment)

Steps to reproduce the bug

Write some c# code calling PackageManager to mount, stage, and register an msix package.
Run it outside of a container to show it works.
Put it in a package to show the staging action fails.

Expected behavior

We expect it to work.

Was on WIndows 11 h5h2 (which is not in the OS pulldown list of this report dialog).

Screenshots

No response

NuGet package version

latest

Packaging type

Packaged (MSIX)

Windows version

Insider Build (xxxxx)

IDE

No response

Additional context

No response

[mominshaikhdev]

@DrusTheAxe