Category List dropdown doesn't expand on clicking its title in the Inspector when Sprite Library Asset is selected in the Project window, refer attached video.

Steps to repro:
1. Create a new project with a 2D Template
2. Project > Create > 2D > Sprite Library Asset
3. Inspector > Add category in the List
4. Try to expand the Category List dropdown by clicking its name

Actual Result:
Category List dropdown doesn't expand on clicking its title

Expected Result:
Category List dropdown should expand on clicking its title

Occurring on:
2021.1.0a7, 2020.2.0b13

Working fine on:
2021.1.0a6, 2020.2.0b12, 2020.1.15f1

Environment:
Occurring on Windows 10 & Mac 10.15.

Workaround: On clicking the dropdown icon it's expanding.