color_by assigns the same color to all categories when using a nested object path

[dietmar]

Potentially related to #101

It seems to me that using a nested payload path in color_by works only partially: There is no error and the legend at the top is populated correctly. But the same color is assigned to all categories.

See screenshot: My data contains 7 different values for metadata.product. They show up in the legend. The currently selected point has the product name starting with lower-case "a". Clicking on the legend item for that product hides/shows this point and all other points belonging to this product.

But all points are light blue.