-Unable to create a transition between animation states.
-Unable to select Animation state due to this drop endpoint for transition is not detected.
-Sometimes Animation state selected and allow to create transitions, but after that, it does not allow to create a transition with another animation state.

Steps to repro:
1. Create a new Project.
2. Assets > Create > Animator Controller.
3. Right-click > Create State > Empty.
4. Create 2 new Animation state.
5. Create transitions between:
-New State >> New State 0.
-New State 1 >> New State.
-New State 0 >> New State.

Actual Result:
Unable to create a transition between animation states smoothly.

Expected Result:
Transitions should be created smoothly.

Reproducible in:
2020.1.0a23, 2020.1.0a21.

Working Fine in:
2020.1.0a20, 2019.3.0f6 (27ab2135bccf).

Environment:
Occurring on Windows 10 & Mac 10.15.