ApprovedShellExtension issues

I am having issues with a repackaging of a vendor application into MSIX. The problem is with "Classic" ShellExtension ContextMenus I am adding by hand. I have been trying to use what is documented in

desktop7:ApprovedShellExtension - Windows UWP applications | Microsoft Learn

 

I am finding two issues that could use Microsoft to advise and/or document and/or fix.

1.  Adding in the extension seems to imply by documentation of the above link, that <uap4:CustomCapability Name="Microsoft.classicAppCompatElevated_8wekyb3d8bbwe"/> should be included in the package to ensure the extension is usable.
2. Adding the CustomCapability allows the package to be generated, however AppInstaller does not allow the package to be installed due to a "file not found" error. THe AppXDeploymentServer/Microsoft-Windows-AppXDeploymentServer/Operational log has an event warning with EventId=9521 with text "CC file pattern \\?\C:\Program Files\WindowsApps\{package name}\*.sccd, hresult 0x80004005, error 0x02, index 0".  From looking around it seems like I may need to include a file with the sccd extension, however what the contents of that file, and whether the sccd file itself needs to be signed (and by who) is not clear, nor documented.

Some clarity, and improved documentation (possibly including whether or not this is really important to include the CustomCapability, beyond the existing documentation that implies that it is) would be appreciated.