When granting access for a user in a given child page, if restrictions apply in the page's parent that are overwriting the restriction settings of the child, the user won't be granted access to child page.

It would be best to make things clear to the user which pages they will have to request access to would make things more intuitive in terms of the path to access.

For example, let them know that page is a child of another page, and he needs to ask for access in the parent page pages.

Another alternative (more difficult to be implemented) would be to include the parent page in the "request access" link, and that it should be as clear as possible that all of the requests will need to be granted for the bottom page to be reachable.