Well… this one will have to be filed under T for ‘Twilight Zone’ …
Having renamed the machine running mediator, I changed the XBD settings referring to the host name (in the setMediatorEnvironment.bat, windows registry etc…) and got everything running without reinstalling.
And magically I can now modify my default message properties via SMH…
I suppose the reason was a rogue setting somewhere, however can’t shed any more light on this.