Does "Find Image on Screen" Not Work if Mission Control Is Enabled?

I am trying to find a color with "Find Image on Screen". The colors are desktop backgrounds (red, blue, green) that are visible when Mission Control is enabled.

This should be easy. But even if I limit the area to the upper part of the screen, KM does not recognize the colors.

Does "Find Image on Screen" not work if Mission Control is enabled? Thanks!

Sure it does.

Use a display-text-in-window action or a notification to make sure your macro is actually working.

Chances are you've missed a step somewhere.

When taking your screenshot with 4 you need to hold down both the Control and Option keys.

This copies the screenshot to the clipboard for pasting – and prevents the system from adding shadow effects to the screenshot (which can foul up find by image).

(At least that's how things work on macOS 10.14.6 Mojave.)