In code when SiteMap.CurrentNode is first referenced, "ORA-24912: Listener thread failed. Failed to get IP address of host" is thrown. I do not see an entry in user_change_notification_regs view for Web applications IP address. So, thoughts are SiteMap providers is not correctly initializing notification.
Schema user has "DB Notification Permission" and InstallOracleXXXXX.sql scripts ran successfully.
Hosted on Windows 2008 R2 / IIS 7.5 - I'm told by Server administrator ports are available and local firewall is disabled.
Additional note... all other Oracle Providers work correctly on Web server. OracleSiteMapProvider works correctly when hosted from local / laptop development server (connected to the same DB).