Official instructions to create Microsoft Store app bundle for submission

[zipswich]

I have migrated an app from UWP to WinUI 3 and VS no longer generates the .appxupload file. In other words, the bundle is not generated with the regular app publishing process in VS:

1. Right-click the app > Package and Pubish >Associate App with the Store > Selected the published app...
2. Right-click the app > Publish > Create App Package... > Microsoft Store as... >Select the Release versions > Create

It generates a .msix file. Microsoft Partner Center does not allow me to submit myapp_x64.msix because "A previous submission for this app was released with a Windows 10/11 .msixbundle or .appxbundle. Subsequent submissions must continue to contain a Windows 10/11 .msixbundle or .appxbundle."

It seems that I need to use MakeAppx.exe to create the bundle for submission. Could anyone point me to the official instructions for this?

I tried to use MakeAppx.exe to create a bundle from the folder created by VS's package creation process: "...\bin\x64\Release\net8.0-windows10.0.22621.0\win-x64\AppPackages\Foo.Windows_6.0.17.0_x64_Test" and Got the following:

MakeAppx : error: Bundle creation failed.
MakeAppx : error: 0x8051100f - The specified package format is not valid: The zip archive is missing the end of central directory marker.

[#2]

Off the top of my head (without going to Visual Studio to verify) I seem to remember that you have to use a "publish" menu in visual studio to generate the .appxupload file.

[#3]

I realized that I was not clear in my question, so I have just edited the question to make it clearer.
I published the app a long time ago with VS and went through the steps in VS to generate the package for publication or package updating numerous times. My main point is that the exact same steps do not generate the package acceptable to the Microsoft Store for an app migrated to WinUI. In other words, the package generated by VS specifically for the Microsoft Store is not acceptable to the Microsoft Store.