Summary
Can't find a page of a certain page type that was recently deployed/staged?
Kentico Xperience page types need a site association to work correctly. If a page type is not associated to a site, content editors will not be able to use / choose that page type in the Pages app when creating a new document in the content tree.
This situation can be caused by the Content Staging app inside of Kentico Xperience not always being used correctly to sync the page type from a development environment to a production environment. Content Staging still works to create the page type in the target environment but silently misses associating the object to the target site. This check looks for any instances of this issue and reports it.