Before even factoring inclusions/exclusions into account, our analyzers have default associations with code files based on file extensions. Unless the file extensions you’re interested in are associated with the XML analyzer, it won’t pick them up even if otherwise they are “in scope” of the project…because it has no idea that they are XML files.
You can fix this by visiting the Language preferences (either at the project or global levels) and registering the additional extensions with our XML analyzer. Here’s a screenshot to show you where I’m talking about: