To explain this problem in a different way:
- In a chart, select the "change color" drop-down (specifically I choose one of the continuous shading options, but any is fine). Many color options are listed, each shows a list of colors to be assigned to the chart.
- You would expect the colors in the list of colors selected in "change color" to be distributed in the same order as the "Select Data" pop-up, "Legend entries (Series)" list. For example, if 10 colors are in the selected list, you would expect the first color assigned to the first charted element, the second color to the second charted element, etc... (looping at the end, if there are more charted elements than colors).
As time go on, as the "Legend..." list is added to and deleted from, this is no longer the case. Especially when a continuous shading is selected, and you get a hap-hazard assignment of colors when compared to the listed series. Not quite hap-hazard: it looks to assign the first element to some nth color (not the first listed color), and cycle through the colors from there.
I see this in other ways too: I'd also expect "option+up/down" arrow to traverse elements in the series in the same order as listed in the "Legend..." list. That order is lost too.
I also see an occasional error that is very similar: while the chart elements are shown in the chart properly (in the order listed in the "Legend..." list), a data table at the bottom will sometimes place an item in the middle of the chart at the end of the data table. This is fairly rare (once a month).
