Additive Selection not working for vtkScatterPlotMatrix

I’m rendering a scatterplot matrix in VTK, but the additive selection (VTK: vtkScatterPlotMatrix Class Reference) is not working as it should.

Only when I change the selection method for the big chart to SELECTION_PLOTS using:

matrix->GetMainChart()->SetSelectionMethod(vtkChart::SELECTION_PLOTS);
matrix->GetMainChart()->SetSelectionMode(vtkContextScene::SELECTION_ADDITION);

it seems to work ONLY for the big plot whereas I want the corresponding selected points to be selected in the smaller plots as well like they get selected in the normal selection mode.

Any ideas on how I can fix this issue?