zSmooth is not working for Contour Plot

[MaheshPunna]

open Plotly.NET

let z = [[10.; 10.625; 12.5; 15.625; 20.];
           [5.625; 6.25;8.125;11.25;15.625];
           [2.5; 3.125; 5.; 8.125; 12.5];
           [0.625; 1.25; 3.125; 6.25; 10.625];
           [0.; 0.625; 2.5; 5.625; 10.]]

Chart.Contour(data=z,X=[-9; -6; -5 ; -3; -1],Y=[0; 1; 4; 5; 7],zSmooth=StyleParam.SmoothAlg.Best)

Current Behavior: