I'm having an issue using the InitialContext(Hashtable env) constructor as well.
It does work if you set the properties you need via JVM args with -D, or System.setPropery(...) at runtime.
The properties you need to set (that work for me, atleast) are:
System.setProperty("org.omg.CORBA.ORBInitialHost", "localhost");
System.setProperty("org.omg.CORBA.ORBInitialPort", "7037");
7037 is the IIOP listen port, this is different from the default since I have a custom domain. I believe the default is 3700, but you can see what it is set to in the admin console under Configuration > ORB > IIOP Listeners
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