Got further with the problem:
the output signal was missing the preceeding / on the "Outputs Setup" pane.
With the signal name changed to /Icore/RWL_B0_WN<0> the simulation ran to completion.
The input.scs file now has it in the save statement as Icore.RWL_B0_WN\<0\>
But now, when double clicking on the output I get this message:
ERROR (WIA-1006): Unable to plot expression <VT("/Icore/RWL_B0_WN<0>" .....
*Warning* Wave1 is not a waveform object that can be displayed and
will be DELETED automatically.