D800E Manual exposure mode and Auto ISO

On the D800E, I would have thought that once you put the camera in manual mode, the Auto ISO should also switch to fixed ISO.  I usually shoot with Auto ISO on, and 'A' aperture priority mode.

I was shooting some shots the other day and needed manual mode, so I put the camera in manual mode, but the shot looked the same as when I had it in auto mode. I took a few more shots and no change, even with changing the shutter speed, or aperture - the shots looked the same as before.  Then I noticed I still had Auto ISO on.  When I shut it off, then I had full manual exposure control.

Is this correct, that Auto ISO doesn't auto-shut-off when you put the camera in manual exposure mode?