I’m having the same issue on shared SSL. I am able to view the site at https://host.mysite.com/~username/ and the login screen at https://host.mysite.com/~username/wp-login.php but when I try to log in it takes me back to the login screen with the user name filled and password empty with the url showing
https://host.mysite.com/~username/wp-login.php?redirect_to=https%3A%2F%2Fhost.mysite.com%2F~username%2Fwp-admin%2F&reauth=1
If I go back to https://host.mysite.com it shows that I am logged in, but trying to go to site admin redirects me back to the login again.
