I have a WordPress multisite installation example.com, with subdomains example.com/foo, and example.com/bar.
I'm trying to change the site name of example.com/foo to foo.example.com.
Normally I just change this in Network Admin > Sites, and then change a particular site's name in the "Site Address (URL)" field - e.g. to foo.example.com
Having done this, foo.example.com now points to the right homepage... But all subsequent pages are "Not found". E.g. example.com/foo/news-story had content, but foo.example.com/news-story is "Not found".
What have I missed?