I don't remember about the older versions, but I am on the cloud version of Photoshop now and Color Range works in CMYK now. Don't know if it always did or not.
As far as Sbrems issues. I can only guess that there is something not activated in your layers. (For example), I can have 2-5 layers in the layers window, but if I have none of the layers activated, or even all of them, then for some reason these days, it won't let you do things. Selections is one of them. This gets me some times. It takes a few times to remember whats happening. in order to make a selection, you need a layer activated even if you are selecting while in channels. Yep.
