Menu item screen capture results in monochrome image If I use the sequence Command-Shift-4 Spacebar to capture a menu selection, the resulting images are monochrome. I'm on Yosemite and the result is the same on two devices. Any idea what's going on? All other screen captures are in color. Skitch app Menu Snapshot option gives the same result.

BTW I've used to use the Comm-sh-4 crosshair capture but just at the very moment you lift the cursor to complete the drag, something causes the cursor to select the next menu item, so you capture the menu item without it being highlighted.
The screenshot isn't monochrome, but rather the highlight of the menu isn't ‘composited’ correctly in the screenshot. If you screenshot a menu with other colour in it (for example, System Preferences View menu), you'll notice those colours remain and just the highlight changes from blue to grey.

This bug has been around in macOS for as long as I can remember, and has been fixed in the developer preview of macOS 10.14 Mojave to be released later this year.