Reproduction steps:
1. Open the “HDRPSkyBug” project
2. Open the “SampleScene” scene
3. Open the Rendering Debugger window (Window > Analysis)
4. In the Lighting tab enable “Display Sky Reflection”
5. Observe the displayed sky reflection at the top left of the Scene/Game view
Expected result: the sky reflection does not contain black/empty spots
Actual result: the sky reflection contains black/empty spots meaning the indirect lighting is not contributing any lighting from the sky
Reproduced in: 2020.3.42f1, 2021.3.13f1, 2022.1.21f1, 2022.2.0b15, 2023.1.0a19
Reproduced using: Windows 11, macOS Monterey 12.0.1 (Intel)
Workaround: set the Ambient Mode on the Visual Environment to static and use an HDRI sky to provide some lighting contribution even if it's incorrect. Comes with the overhead of having an additional sky and reflection map
Notes:
1. Expected result can be seen by selecting the “Volume Global“ GameObject and enabling the “HDRI Sky” override
2. No Rendering Debugger in 2020.3.42f1. Instead, see whether the actual sky contains any black spots
3. In newer versions (e.g. 2022.1.21f1) the custom “New Sky” override seems to be invisible in Inspector
4. In some versions (e.g. 2023.1.0a19) the displayed sky reflection is completely black/empty
5. Also reproduced in Player