LineGeometryModel3D Bounds not updating when LineGeometry3D.IsDynamic = true

[sjc9999]

I'm using with LineGeometry3D with IsDynamic = true as shown here:

LineGeometry3D lineGeometry = new LineGeometry3D()
{
PreDefinedVertexCount = steps,
PreDefinedIndexCount = (steps - 1) * 2,
IsDynamic = true,
};

LineGeometryModel3D lineGeometryModel = new LineGeometryModel3D()
{
Geometry = lineGeometry,
Color = Colors.Violet,
Thickness = 1.7,
};

When I update the LineGeometry3D Positions and Indices the Bounds update as shown here:

lineGeometry {HelixToolkit.SharpDX.Core.LineGeometry3D}
Bound {Minimum:X:-2.4942286 Y:-1.0346919 Z:-0.5175258 Maximum:X:-0.03416315 Y:0.90985554 Z:0.6107951}
BoundingSphere {Center:X:-1.5894607 Y:-0.20421538 Z:-0.0045135114 Radius:1.8362526}

But the LineGeometryModel3D doesn't update as shown here:

lineGeometryModel {HelixToolkit.Wpf.SharpDX.LineGeometryModel3D}
Bounds {Minimum:X:0 Y:0 Z:0 Maximum:X:0 Y:0 Z:0}
BoundsSphere {Center:X:0 Y:0 Z:0 Radius:0}
BoundsSphereWithTransform {Center:X:0 Y:0 Z:0 Radius:0}
BoundsWithTransform {Minimum:X:0 Y:0 Z:0 Maximum:X:0 Y:0 Z:0}

Everything works fine as long as the camera is pointed to 0,0,0 and the rotation is around that point
but if I focus and rotate on a point on the line the line disappears / reappears as I rotate and zoom in / out

I have tried calling these methods on LineGeometry3D but it makes no difference:

UpdateVertices();
UpdateTriangles();
UpdateBounds();

I can send you a test solution I created if you want.

[holance]

Please upload the sample.

[sjc9999]

OK here is the code please see the readme.txt

DynamicTest.zip