InterPlot not honoring Timeout setting

I'm trying to plot a large raster file and InterPlot keeps timing out at 30 minutes.  I've changed the setting of
IPLOT_MSTN_TIMEOUT
in the iplot.cfg to several different values, from 0 which is supposed to set no timeout, to 180, to 18000, and still it times out after the default setting of 1800 (30 minutes).  I tried replacing the iplot.cfg with the default iplot.def file, same result.  I get the same results with the Iplot Microstation interface, Interplot Organizer, and iplot command line.
I'm using InterPlot 8.11.07.126 and Microstation 8.11.07.443

Any help appreciated !