Set colors for specific values within charts (other than bar charts)

I’m trying to set certain colors for values within an aggregate model (or any model, really).  Say the values are either “Off Track” (Gray) or “On Track” (Green).

I have them sorted alphabetically, so Off Track becomes Group 1, On Track is Group 2.

But when the model returns 0 records for Group 1, and [All] records for Group 2, the donut chart displays Gray, because that is the first color listed in the colors section.

Rob Hatch posted a snippet here of how you can “lock” colors in a bar chart; it works fabulously for those, but he wasn’t able to modify it for other chart types.  Wondering if anyone knows how we can get it there?
https://community.skuid.com/t/have-certain-colors-represent-certain-values-in-charts