Bindings dropdown Icon is not getting clicked in Playable Director.

Steps to repro:
1. Create a new project.
2. Gameobject > Create Empty > Add Playable Director component.
3. Windows > Sequencing > Timeline.
3. Create a Timeline for Empty Gameobject.
4. In the Inspector click on Bindings dropdown arrow Icon.

Actual Result:
Bindings dropdown arrow Icon is not getting clicked.

Expected Result:
Bindings dropdown arrow Icon gets clicked.

Reproducible in:
2020.1.0a4, 2019.3.0b3, 2019.3.0a7.

Working Fine in:
2019.3.0a6, 2019.2.0f1.

Environment:
Windows & Mac 10.14.