activity monitor CPU history now shows single graph in Floating window - how to restore display of all eight (8) cores?

Since restarting, the Activity monitor floating CPU history Window now shows all eight cores collapsed into one. This is NOT the behavior I expected after doing some research and finding this article OS X: Activity Monitor shows one CPU Usage graph on systems with more than four cores - Apple Support

Not a show stopper but I've been investigating performance issues on a new machine and this "new" behavior has me flummoxed and suspecting a newbie error.

Thanks!