Python Manager MSIX does not install. Secureden?

Install source and version

• Installed from the Windows Store
• Installed with the MSIX from python.org
• Installed with the MSI from python.org
• Installed with winget install 9NQ7512CXL7T

Version: 26.1.240.0

Describe the bug
It doesn't install. I click install, it gets to 98%, I then get this error:

App installation failed with error message: AppxManifest.xml(150,26): error 0x80070020: Cannot register the PythonSoftwareFoundation.PythonManager_26.1.240.0_x64__3847v3x7pw1km package because the following error was encountered while registering the windows.appExecutionAlias extension: The process cannot access the file because it is being used by another process.
. Try again and contact the package publisher if the problem persists. (0x80070020)

To Reproduce
Steps to reproduce the behavior:

1. Click install

Expected behavior
I expect it to install.

Additional context
I can't see any specific logfiles in %TEMP% that go with python manager

I work in a "secure" IT environment (using secureden), and each instance of admin elevation has to be approved by IT.
However the installer/UAC is not asking me to elevate to admin, so I'm not sure if that's the issue. I can't see a way in file explorer to run the .msix as admin, as the "right click > run as admin" option is only for .exe, and I don't fancy asking IT for a admin command prompt :)

The "windows store" is disabled by IT policy.

Start by reproducing the MSIX installation failure on Windows using the reported version and review the AppxManifest error, especially the windows.appExecutionAlias registration failure. The issue names no repository files or tests; done means determining why installation reaches 98% and providing a verified fix or clear workaround for the affected secure environment.