Errors when publishing Delphi 10.1 Berlin application to the Microsoft Store with .msix or .msixbundle

Question

I have created a .msix for my Delphi app, which installs fine locally, and WACK (Windows App Certification Kit) passes with no blocking issues.

I have checked that the AppxManifest.xml identity and product metadata matches the package info from the App Store page, and this matches the self-signed key I have generated.

When I upload to the App Store, I get the unhelpful error message below (both text and image):

You must upload at least one package. If you are using market groups, then each market group must have at least one package.

You must provide a package that supports each selected device family (or uncheck the box for unsupported device families). Note that targeting the Xbox device family requires a neutral or x64 package.

The package DataMystic.WordPipe.msix is taking a long time to process. If this isn’t completed soon, try refreshing the page, or remove the package and then upload it again. If you continue to see this issue, contact support.

You must fix all package validation errors before submitting.

The error messages seem patently wrong, and are definitely unhelpful in knowing what failed.

I have also tried using a .msixbundle / .msixupload file, with exactly the same results.

I did have earlier issues with using my digital signing key, but have since been told to use a self-signed key (especially as the CN of my hardware digital key does not match the CN allocated by the Store).

I am using Delphi 10.1 Berlin, and there doesn't seem to be any support for this.

1. Delphi 10.4 docs have this: https://docwiki.embarcadero.com/RADStudio/Sydney/en/Submitting_Your_App_to_the_Windows_Store

2. I don't have Project | Options | Provisioning as per https://blogs.embarcadero.com/deploying-windows-10-apps-through-the-microsoft-store-1863306656/