Spike Sorting on Brainstorm Install w/o Matlab

We recommend that before trying to use the tools from the e-phys toolbox, you start by learning how to use Brainstorm with the introduction tutorials (section "Get started"), following them at least until #19.
https://neuroimage.usc.edu/brainstorm/Tutorials/ChannelFile#Review_vs_Import

I was able to run UltraMegaSort, but I get this error:

This function was written by @mpompolas, I have never used it myself.
In order to fix this error, I would need your help in order to reproduce it on my computer first.
Could you please share a short example file, and detailed step-by-step instructions from the "Review raw file" needed to reproduce the error.

You can find a recent example of bug resolution here: