I found what I think is a bug using Mirror and Color. Mirror a body and go to Tools. Select both bodies then click on Color and the mirrored body becomes dark. It appears to stay dark until you physically alter it after which you can undo the change to get it back, and, the color is now corrected.
You don’t have to select both bodies initially. You can select only the mirrored body, go to Color and it will be dark. If you click on Color before you select the mirrored body, Color appears to work correctly.