I configured a RDP bookmark to single sign on users to our terminal server.
All works fine if the username contains no umlauts.
Some of our users have an Ó, Ó or Ó in her username and here the SSO fails.
The Juniper RDP-client starts the session and the terminal server logon-screen appears with the correct username and a blank password field. If the user enters his password the logon is successful.
I deleted the Ó from an affected username and then the SSO works without a problem.
I think it is not supported, like a % in your password (for sso to webmail)
but it can be a bug - contact JTAC for an answer