Bug in X-Means

Terpdog

I am running version 9.10 and did a cluster analysis on a single numeric variable in Auto Model. I performed both K-Means and X-Means clustering. The K-Means was fine but the X-Means gave me an error message that said the input data had only 1 class after pre-process/and or validation splits. This can happen if one or several of your classes are extremely rare. This error message makes no sense to me in the context of clustering with a numeric variable. Is this a bug?