I have a multisite install with three domains; the primary, root install, and two subdomains mapped to top-level domains. I upgraded WordPress from 3.42 to 3.51, and although the top-level domains still go to the correct sites, the only "Dashboard" I can get to within the WP admin panel is the main site.
I can see the three separate sites by going to My Sites, Network Admin, Sites - but each of the links to the Dashboard goes to the primary site Dashboard. If I manually type in the URL to the separate wp-admin pages, I can get to the individual dashboards.
The main site is kindersbbqfairfield.com, and the two subdomains are danville.kindersbbqfairfield.com and pleasanton.kindersbbqfairfield.com, mapped to kindersbbqdanville.com and kindersbbqpleasanton.com, respectively.
I have screen shots of the admin panel if that will help.
What am I missing? What changed in 3.5.1?