Baked shadows are missing on lightmapped terrains when baking with GPU PLM on macOS

Steps to reproduce:

1. Download and open LightmapAA.zip project
2. Open TestScene03
3. Make sure that Progressive GPU is selected as the baking backend
4. Click on Generate Lighting

Expected behavior:

• Baked shadows from other objects and self-shadows are visible on the terrain

Actual behavior:

• All baked shadows are missing on the terrain

Notes:

• Reproduces in 2023.1.0a4, 2023.1.0a5, 2023.1.0a6
• Affects GPU PLM only; CPU PLM is unaffected
• Affects macOS 10.15.7 (19H1922); it does not affect Windows machines
• Reproduced on MBP 2019 using AMD 5500M GPU
• Does not reproduce on MBP (M1), OSX12.5, Unity 2023.1a6 (under Rosetta)
• Does not reproduce on MBP (M1), Unity 2023.1a25 (ARM64)
• Unable to determine the FAV due to this issue: [Internal link]