In Skinning Editor, the Highlighter of the slider handle is not getting refreshed with the movement of a slider.

Steps to repro:
1. Create a new project with a 2D template.
2. Window > Package Manager > 2D Animation.
3. Import any sprite into the Unity project.
4. With the sprite selected in Assets, open Sprite Editor.
5. Sprite Editor > Skinning Editor > Visibility Tool > Enable
6. Slide "Bone visibility" slider.

Actual Result:
The highlighter of the slider handle is not getting refreshed with the movement of a slider.

Expected Result:
Highlighter of the 'slider handle' refreshes with the movement of a slider.

Reproducible with: 2020.1.0a17, 2020.1.0a16, 2020.1.0a15, 2019.3.0f5, 2019.3.0f4.

Working Fine with: 2020.1.0a14, 2019.3.0f2.

package version found: 4.1.0, 4.0.0, 3.0.5

Environment: Windows 10 and macOS 10.14