As the title says CGDisplayCopyAllDisplayModes does not appear to return ALL of the display modes. I've attached a screenshot showing a list of the modes returned by CGDisplayCopyAllDisplayModes. Notice that a CGDisplayMode with the currently used mode ID# 13 is not in the list. My second screen, a non-Retina display, seems to behave as expected.
How do you find 'all' of the CGDisplayModes for an Apple Studio Display?