Kuba:
Attached repro didn't reproduce it for me, but the repro from the duplicate https://fogbugz.unity3d.com/f/cases/1244786 did.
Issue introduced by https://ono.unity3d.com/unity/unity/pull-request/104619/_/lighting/tiled-ray-buffers.

Steps to reproduce:

1. Open the attached repro project
2. Clear baked data
3. Make sure Progressive Updates are ON
4. Click Auto-Generate
5. Get stuck in endless loop

You can stop the loop by disabling Progressive Updates, or changing the backend to CPU.

Could not reproduce on: 2020.2.0a10, 2020.2.0a9

Notes:
- Also Reproducible in URP and HDRP, starting from Version 8.1.0;
- Reproducible for Progressive CPU and GPU Lightmappers; not reproducible for Enlighten;
- Reproducible in any scene;
- Reproducible only when baking with auto-mode.

It is needed to retest the following duplicate cases when the fix for this case lands:
- https://fogbugz.unity3d.com/f/cases/1244786