grayscale bitmap glitch (crash in PSCC 2017.1.0, glitch in CS6)

When in Grayscale mode, creating a bitmap (Diffusion Dither, input:30px/in, output:30px/in) of a 50% Gray field causes a glitch image in CS6 13.0 x64, and crashes CC 2017.1.0

Question: what is causing the glitch in CS6?