InteractiveEdgeRouter does not appear to be respecting BoundaryCurves of square nodes

This code is adapted from the EdgeRoutingSample DemoRoutingFromPortToPort and DrawEdgeWithPort methods. However, I notice that the nodes within that particular example are ellipses which appear to make the difference.

The nodes are simple squares, but it seems that the inner InteractiveEdgeRouter is not respecting the boundary curves of the square nodes. The boundary curves passed into the InteractiveEdgeRouter are however correct:

private void DoLayout(GeometryGraph geometryGraph)
{
	IEnumerable<GeometryGraph> subGraphs = GraphConnectedComponents.CreateComponents(geometryGraph.Nodes, geometryGraph.Edges);

	SugiyamaLayoutSettings layoutSettings = new SugiyamaLayoutSettings();
	layoutSettings.EdgeRoutingSettings.EdgeRoutingMode = Microsoft.Msagl.Core.Routing.EdgeRoutingMode.Rectilinear;
	layoutSettings.NodeSeparation = 120;
	layoutSettings.LayerSeparation = 120;
	layoutSettings.Transformation = PlaneTransformation.Rotation(Math.PI);

	foreach (GeometryGraph subgraph in subGraphs)
	{
		LayeredLayout layout = new LayeredLayout(subgraph, layoutSettings);
		subgraph.Margins = layoutSettings.NodeSeparation + 200;
		layout.Run();
	}

	InteractiveEdgeRouter portRouter = new InteractiveEdgeRouter(geometryGraph.Nodes.Select(n => n.BoundaryCurve), 0, 0, 0);
	portRouter.Run();
	foreach (Edge tEdge in geometryGraph.Edges)
	{
		FloatingPort port1 = new FloatingPort(null, new Microsoft.Msagl.Core.Geometry.Point(tEdge.Source.BoundingBox.Center.X, tEdge.Source.BoundingBox.Bottom - 10));
		FloatingPort port2 = new FloatingPort(null, new Microsoft.Msagl.Core.Geometry.Point(tEdge.Target.BoundingBox.Center.X, tEdge.Target.BoundingBox.Top + 10));
		ICurve spline = portRouter.RouteSplineFromPortToPortWhenTheWholeGraphIsReady(port1, port2, false, out _);

		Arrowheads.TrimSplineAndCalculateArrowheads(tEdge.EdgeGeometry,
			tEdge.Source.BoundaryCurve,
			tEdge.Target.BoundaryCurve,
			spline, true, false);

		DrawSpline(tEdge, spline);
	}

}

I am aware that the ports appear backwards - i.e. exit at the top and entry at the bottom. This is a deliberate setup to test MSAGL.

Start with the DoLayout example in the issue and trace InteractiveEdgeRouter.RouteSplineFromPortToPortWhenTheWholeGraphIsReady, including the BoundaryCurve values passed to the router. Reproduce the square-node case and compare its routed spline with the ellipse-based EdgeRoutingSample; done means the router respects square node boundaries in this scenario.