Fill Theme Color picks wrong color (I choose green, it paints yellow)

[LiveFreeAndRoam]

This is happening in just one of my Visio documents.  Others behave normally.

When I navigate to Shape Styles > Fill > Theme Colors, it presents a grid of colors.  When I select the lightest-green color (Green Accent 6, Lighter 80%), it actually fills the shape with a "Yellow".


I would guess some color mapping has become confused.  How can I correct this?