Color Range Definition (3): Rendering problem of diverging color palette

Update: Tableau 8.2.4 partially fixed the problem. Still, the fix is biased towards high color. The center is not respected some times. Filed a further bug.

Tableau 8.2.2 fixed some bugs but some are still persisting as chronicled in
Color Range Definition (2): Tableau bug partially fixed in 8.2.2
Color Range Definition (1): a bug in Tableau color editor
Its Tableau case ID is 00742792.

I found some more problems in color range definition. To be precise, it's in the definition of center value under diverging color palette.

We will illustrate using an example where the center value is fixed at 10. Assume that we use a red-green diverging color palette and select the full color range option.

1.Start=9,Center=10,End=11
Use this setting and we get a simple bar chart as below.

 

In the picture we see that the bar at value 10 is rendered in Gray. All values<=9 are rendered in saturated Red and all values >=11 are rendered in saturated Green.

This is all right as expected.

2.Start=10,Center=10,End=11
In this case, I would expect that all values less than 10 be rendered in saturated Red. However I found the result as in the following picture.

All values under 10 are rendered in black. This is not correct.

3.Start=9,Center=10,End=10

In this case, I would expect that all values larger than 10 be rendered in saturated Green and the center value be rendered in Gray. 

The resulting colors for values at Center value (10) and above are not right. 

4.Start=10,Center=10,End=10

In this case, the value 10 could have been rendered in any of the Red, Gray and Green. The most reasonable color for the value 10 would be Gray. However in the following picture, the value 10 is rendered in Green.

In conclusion, in all of the above 4 cases, they would have looked the same in color rendering. However:

in case 2, the lower values are rendered not correctly.

in case 3, the center value and higher values are not rendered correctly.

in case 4, the center value is not respected and not rendered correctly.
In cases 2 and 3, black color should not have been used at all because it is not part of the color palette.

The workbook can be viewed and downloaded here for further exploring.