Actually it mention to restart the appliance after configuring your SSO authentication Configuration. It seems still easy to miss that message 
. I have put a screenshot of that message on my blog to help others who missed it as well to over come the mis-belief that a restart is not required after carrying out that configuration. Here is the post: http://www.virtualizationteam.com/server-virtualization/vcenter-server-appliance-5-5-sso-issues.html
Thanks,
Eiad Al-Aqqad
Blog: http://www.VirtualizationTeam.com
Twitter: Virtualization