Ok, so. this may be an issue?
This is at the top of the schema
<Package xmlns=“http://schemas.microsoft.com/appx/manifest/foundation/windows10” xmlns:uap=“http://schemas.microsoft.com/appx/manifest/uap/windows10” xmlns:mp=“http://schemas.microsoft.com/appx/2014/phone/manifest”>
http://schemas.microsoft.com/appx/manifest/foundation/windows10
is a broken link now