sorry, this was not clear to me.
Have you tries adding the ROI after multi-looking or terrain correction?
@EarthObs the naming conventions for RCM data would be here (under āBeam mode mnemonicsā):
Not sure if anyone is still having RCM reading problems. In SNAP 12, certain RCM datasets were not opening for me again. However, installing the Radarsat Toolbox Polarimetry plug-in made RCM appear on the āImportā ā SAR sensors Menu. And that function successfully opened the data : - )