contour() not working correctly

[xarico10]

When using contour() to create a contour plot with lines only, a filled plot is being created instead.

[X,Y,Z] = peaks;
contour(X,Y,Z)

fig2plotly(gcf, 'offline', false);

Expected and generated (https://chart-studio.plotly.com/~xarico10/709/#/) plots:

Examples on using contour() can be found on:
https://www.mathworks.com/help/matlab/ref/contour.html#responsive_offcanvas

[benaliabderrahmane]

works perfectly in matlab2021a (online mode) please review