To reproduce (following setting is for 5.4.5 STK, but it is also reproducible on higher Magnolia versions):

• set www.test1.com and www.test2.com in the /etc/hosts file
• configure /server/filters/crossSite/resolvers for "demo-project" and "demo-features"
  
• using the link like http://www.test1.com:8080/magnoliaAuthor/demo-project/demo-features/content-templates/article should return 404, because there is no /demo-project/demo-features/content-templates/article

Notes

• The first part of the link (http://www.test1.com:8080/magnoliaAuthor/demo-project/) is correct, but the second part (/demo-features/content-templates/article) comes from a different site, which should be evaluated as non-existent and therefore receive 404. Now it renders the "demo-features" content (which is mapped to www.test2.com domain).
• "http://www.test1.com:8080/magnoliaAuthor/demo-project/foo" correctly receives 404 because there is not any "foo" page