There are two problems with the bar chart report with non-default colour on iOS
1. In a dashboard, if I select a different colour scheme, e.g. I selected "red" instead of the default "green" colour, the custom colour will not show up on iOS, but only show the default colour (e.g. even if I select "red" it still shows up as "green"). However it shows up fine in android and web
2. In a dashboard, if I select Colour saturation for a bar chart, e.g. using its own value and make it shows up as "red" if > x and show up as "green" if <= x, in iOS (iPad, iPhone) when I press the bar, it will not highlight it and will not show its detailed value as well (with default colour, when pressing a bar, the app will focus on that particular bar and show its detailed value). The problem does not exist on android.
For problem 2, I set up the colouring by using its own value for colour saturation, set x (e.g. 0.5) as both Maximum and Minimum value, and set Maximum colour as Red and minimum colour as Green.