When enabling "volumerendering" property, only the lungs volume from "lungs.vtk" is displayed, but not the volume rendering related to "Pic3D.nrrd". The code was debugged and verified that "volumerendering" property was set to "true" value.
// Set the property "volumerendering" to the Boolean value "true" node->SetProperty("volumerendering", mitk::BoolProperty::New(true));
It was tested in the MITK master branch #647640c36bcc` using VS2015 x64 and x32 on a Windows 10 system.