I'm sure this is just a setting I bumped but I'm stuck. My color palette used to show all colors with white in the top left, black in the bottom left and all the colors of the rainbow in a slider on the right. Now it only shows very limited colors. How do I get the full palette back?
After Effects 2020 v17.1.0
macOS High Sierra v10.13.6
The color picker UI puts the selected color channel in the the slider on the right, and the other two channels in that color model in an X/Y plot on the left.
You have R (red) selected, so the slider shows you possible values of red, given the blue and green values selected to the left.
To get back to where you were, select H (hue). The slider on the right will show all the different hues, and the X/Y plot on the left will show saturation running right to left, and brightness running top to bottom.