Realtime Lightmap Preview window lost its 0th index when Player is stopped

Steps to repro:
1. Open the attached project
2. Window > Rendering > Lighting Settings
3. Click on "RealtimeLightmaps" tab
4. Play the scene.
5. Exit play mode.

Actual Result:
The preview window disappears in Realtime lightmap tab.

Expected Result:
The preview window is present in Realtime lightmap tab.

Reproducible on:
2019.2.0a2, 2019.1.0b1, 2019.1.0a6

Working Fine in:
2019.1.0a5, 2018.3.0f2

Note: Refer attached video

Environment:
Windows & Mac