Karin, thanks for catching that oversight. Jonathan, technically "iscellstr" is correct but since the text function allows empty numeric values as the string, I will change it to iscell.
The changes will be in today's update. Thanks!
This is an excellent utility and I appreciate the effort of the creator Ameya Deoras.
I had only minor difficulties accessing the 'Xlabel' and similar attributes. Users should be aware that the "colormap" property is critical for proper visualization (as acknowledged by author).