Optics node issues

I decided to give the Optics node a whirl. It does a good job at clustering - but there’s an issue in that it throws an error when I try and sort a column in the output.
image and log file enclosed - please change the extension to log from xlsx.
have fun. Tell me where I went wrong please.

knime - Copy.xlsx (72.6 KB)

Hi @mazzo

could you share a minimal workflow with me where you can reconstruct this problem.
I tried and failed unfortunately.

Thank you! Iris

PS: Which KNIME Version are you using?