The input argument mkr isn't changing marker's symbol when using swarmchart().

rng(1)
x1 = ones(1,100);
x2 = 2 * ones(1,100);
x3 = 3 * ones(1,100);
y1 = 2 * randn(1,100);
y2 = [randn(1,50) randn(1,50) + 4];
y3 = 5 * randn(1,100) + 5;

swarmchart(x1,y1,'red','+')
hold on
swarmchart(x2,y2,'green','*')
swarmchart(x3,y3,'blue','d')
hold off

fig2plotly();

The previous code should plot 3 different series with 3 different marker symbol (+, * and diamonds), however, they're all being plotted with the default marker symbol.

Expected and generated (https://chart-studio.plotly.com/~xarico10/335/#/) plots:

Examples on using the mkr parameters can be found on:
https://www.mathworks.com/help/matlab/ref/swarmchart.html#mw_b4fe23df-071d-4ceb-991c-c53325d89599