A client has a subpage on a page that he wants to move to the site level. All pages have the same “content” template/blueprint. But only this page can not be moved to site, all other pages on this subpage can be moved to site.
The page that needs to be moved (notice the grayed out Site):
There is no difference (except the content), both are published pages using the same blueprint. Other pages on this subpage can be moved to Site as well, as well from other parent pages, all using the same blueprint. Only this single page is not possible to move to Site.
@texnixe solved it finally. There was a concept page using the same url as the page would get if moving would be possible. But that was not very easy to spot with 40+ concept pages
Maybe an error stating reason why move is not possible, or enforce the move with a different url would be nice on sites with a lot of pages.