Steps to repro:
1. Create new project on Windows and open "SampleScene" scene;
2. In the Lighting window (Window>Rendering>Lighting) press the "New Lighting Settings" button;
3. In the Lighting window enable the Auto-Generate checkbox;
4. Observe the progress bar at the bottom right corner of the Unity Editor.

Expected result:
GI progress bar is updating with the bake progress and disappears after it's completed.

Actual result:
GI progress bar is stuck at "Preprocessing" stage. See attached video.
Regression introduced in Version 2020.2.0.

Hovering over the progress bar makes it disappear.

Notes:
- Reproducible in Version 2021.2.0a4, 2021.2.0a1, 2021.1.0b7, 2020.2.5f1;
- Not reproducible in 2021.2.0a5, 2020.1.17f1, 2019.4.20f1;
- Reproducible only on Windows; Could not reproduce on OSX;
- The issue might not repro everytime. If it doesn't try following:
- Disable the Auto Generate checkbox;
- In the Lighting window clear the baked data;
- Re-enable the Auto Generate checkbox;

- Reproducible for both empty and non-empty scenes containing the baked gameobjects;
- The issue might also reproduce after clearing baked data;
- The issue seemingly has no effect on the actual GI baking and only affects the UI.