OctTree not returning all close objects

[davidebazzi]

I found this situation where not all the curves near to e1 are returned.
Ellipse e1 = Ellipse.Construct();
e1.SetArcPlaneCenterRadiusAngles(Plane.XYPlane, new GeoPoint(-2.6645352591003757E-15, -0.00061799183524513523, -1.4186852022952081E-11), 3.2542739087564954, 1.5707963267948966, 0.78526360536556272);
Ellipse e2 = Ellipse.Construct();
e2.SetArcPlaneCenterRadiusAngles(Plane.XYPlane, new GeoPoint(0.00043698863923324893, 0.00043698863923324893, -1.2655946892266502E-11), 3.2531320020360277, 0.78539843638719131, 0.78553221540911267);
Line l3 = Line.Construct();
l3.SetTwoPoints(new GeoPoint(-10.8194119352, 10.8194119352, -1.8179609362265755E-11), new GeoPoint(-2.30074868929, 2.30074868929, -1.7698803840286583E-11));
Line l4 = Line.Construct();
l4.SetTwoPoints(new GeoPoint(2.30074868929, 2.30074868929, -1.2655946856715126E-11), new GeoPoint(10.8194119379, 10.8194119379, 5.5347351477650072E-12));

GeoObjectList list = new GeoObjectList(e1, e2, l3, l4);

OctTree<IGeoObject> tree = new OctTree<IGeoObject>(list.GetExtent(), 0.001);
tree.AddObject(e2);
tree.AddObject(l3);
tree.AddObject(l4);

IGeoObject[] nearObjects = tree.GetObjectsCloseTo(e1);

nearObjects contains only l4, but I expect also e2.

If I use this code, then I get both.
BoundingCube bc = e1.GetBoundingCube();
bc.Expand(0.0001);
IGeoObject[] nearObjects2 = tree.GetObjectsFromBox(bc);

The "problem" is that the OctTree nodes are splitted right on the extrema of e1 and e2.
In blue the 4 curves.
Red lines is the bounding cube of the 4 curves.
Green lines are the bounding cubes of the nodes of the octtree

Result.cdb.json

1. Is that correct?
2. There is a way to get the objects of the "near" node without increasing the size of the BoundingCube? Because I don't know it a priori that I am in this situation.