2X RDP Client for Windows x46 (12.0 (build 2212) - SSO featu

Support,

When we install the 2X RDP Client for Windows x46 (12.0 (build 2212) on our 2008 R2 x64 RDS servers, the SSO option is available to install/enable via the General tab under options.

But trying the same install on a 2012 R2 RDS server the entire SSO option is missing the General tab under options. That being said the SSO checkbox is there when creating a connection, yet it is greyed out.

What options do we have to use the SSO option in the RDP client under 2012 R2 as an RDS session host?