Currently, the very first colour change keyframe logged in a Visual State doesn't log the value selected in the colour picker, and seems to snap back to the previous value.
Video attached.

Repro Steps:
1) Create a Project with a MainPage.xaml
2) Introduce a Button to the Page
3) Right-Click on the Button, and from the context menu navigate to 'Templates', 'Button', then 'Create'.
4) Navigate to the Animation/VisualStates Panel, and select any Visual State (MouseOver is a good choice).
5) Select the Border Element, present in the default Template's hierarchy.
6) From the Properties Panel select the 'Background' Property to open the colour picker.
7) Click anywhere on the colour spectrum to select a new colour. The bug is easiest to observe when moving the picker circle to the top-right corner of the chart.

Observe how the colour picker circle snaps away from the selected zone on the colour picker.

Expected Results: Selecting a colour in the colour picker immediately applies it.

8) Click on another area of the colour picker.
Observe how subsequent colour pickings are applied as expected.