I am using Defender to mask the login screen. When I try to visit the dashboard of one of my sites from the "My Sites" dropdown menu, I am redirected to the Pro Sites link. In order to access the dashboard, I have to go to My Sites > Network Admin > Sites.
It appears that once I log in on the 2nd site (SamuelHillLive), the first method works. Seems to be some kind of pesky bug somewhere.