Using the latest snapshot from GitHub, I find that, if I use segments in my genome, CMA-ES silently gets stuck before the first generation is evaluated. Attached is a MWE. I'm guessing that some background thread has silently crashed while the main thread was waiting for it? Siggy -- Ph.D student in Computer Science, George Mason University CFO and Web Director, Journal of Mason Graduate Research http://mason.gmu.edu/~escott8/