"Source Object" and "Setting" dropdown list doesn't expand on clicking its title under the "Blend Constraint" component, refer attached video.

Steps to repro:
1. Create a new project
2. Package Manager > Animation Rigging > Install
3. Hierarchy > right-click > Create Empty
4. Inspector > Add Component >Animation Rigging > Blend Constraint > Add
5. Hierarchy > Empty Object > Inspector >Blend Constraint > Click on Source Object tital

Actual Result:
"Source Object" and "Setting" dropdown doesn't expand on clicking its title

Expected Result:
"Source Object" and "Setting" dropdown expand on clicking its title

Occurring on:
2020.2.0a18, 2020.1.0b16 with Package Version 1.0.2, 0.3.3-preview, 0.3.2-preview
2019.3.0a1 with Package Version 0.1.2-preview

Environment:
Occurring on Windows 10 & Mac 10.15.

Workaround: On clicking dropdown icon it expands.