Bone and Geometry slider visibility icons are missing in the Skinning Editor from Sprite Editor window, Refer to the attached screenshot.

Steps to repro:
1. Create a new project with a 2D Template
2. Project > Create > 2D > Sprite > Square
3. Inspector >Sprite Editor > Skinning Editor
4. Create Bone
5. Generate Geometry
6. Enable Visibility Panel

Actual Result: Visibility icons are missing for Bone and Geometry slider in the Skinning Editor

Expected result: Bone and Geometry slider icons should be visible clearly

Occurring in:
2021.1.0a7, 2021.1.0a2 with package version 5.0.3

Working fine in:
2021.1.0a1, 2020.2.0b13, 2020.1.12f1 with package version 5.0.3, 4.2.6

Environment:
Windows10 and macOS 10.15