When using waterfall() to create a waterfall plot, which is a mesh plot with a partial curtain along the y dimension, a very different plot is generated. The generated plot isn't filled, which makes it very hard to understand.

[X,Y] = meshgrid(-5:.5:5);
Z = Y.*sin(X) - X.*cos(Y);
waterfall(X,Y,Z)

fig2plotly(gcf, 'offline', false);

Expected and generated (https://chart-studio.plotly.com/~xarico10/823/#/) plots:

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