Cannot import STeP layers with 7.4.0.

Hello. I've got the following code fragment, in which I'm trying, in several ways, to detect to which layer[s] a shape is assigned:

      TDF_LabelSequence Labels; LayerTool->GetLayerLabels(Labels); std::cout<<Labels.Size()<<std::endl;
      for (Standard_Integer i=1;i<=Labels.Size();++i)
        std::cout<<LayerTool->IsSet(Shape,Labels(i))<<" ";
      std::cout<<std::endl;
      Handle(TColStd_HSequenceOfExtendedString) aLayerS; Standard_Boolean a=LayerTool->GetLayers(Shape,aLayerS);
      std::cout<<a; if (a) std::cout<<" "<<aLayerS->Size(); std::cout<<std::endl;

All of them work on 7.3.0, but don't on 7.4.0.

I tracked this to the changes in XCAFDoc_ShapeTool::FindShape (XCAFDoc_ShapeTool.cxx:291).

Is this  a regression? Would taking the previous version of this method have any side-effect?

Or am I doing it wrong? Is any of the above a supported way to get shape's layer info? How should I do it instead?

Thanks in advance.