So I tried to bake light for hdrp and I found that baking reflection probe produce error. Two actually.
I used Unity 2020.1 and latest HDRP from package manager v9.0.0-preview.33.
NullReferenceException: Object reference not set to an instance of an object
UnityEngine.Rendering.HighDefinition.HDRISkyRenderer.Build () (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/Sky/HDRISky/HDRISkyRenderer.cs:24)
UnityEngine.Rendering.HighDefinition.SkyUpdateContext.set_skySettings (UnityEngine.Rendering.HighDefinition.SkySettings value) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/Sky/SkyUpdateContext.cs:39)
UnityEngine.Rendering.HighDefinition.HDCamera.UpdateCurrentSky (UnityEngine.Rendering.HighDefinition.SkyManager skyManager) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/RenderPipeline/Camera/HDCamera.cs:774)
UnityEngine.Rendering.HighDefinition.SkyManager.UpdateCurrentSkySettings (UnityEngine.Rendering.HighDefinition.HDCamera hdCamera) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/Sky/SkyManager.cs:230)
UnityEngine.Rendering.HighDefinition.HDRenderPipeline.TryCull (UnityEngine.Camera camera, UnityEngine.Rendering.HighDefinition.HDCamera hdCamera, UnityEngine.Rendering.ScriptableRenderContext renderContext, UnityEngine.Rendering.HighDefinition.SkyManager skyManager, UnityEngine.Rendering.ScriptableCullingParameters cullingParams, UnityEngine.Rendering.HighDefinition.HDRenderPipelineAsset hdrp, UnityEngine.Rendering.HighDefinition.HDRenderPipeline+HDCullingResults& cullingResults) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/RenderPipeline/HDRenderPipeline.cs:3071)
UnityEngine.Rendering.HighDefinition.HDRenderPipeline.Render (UnityEngine.Rendering.ScriptableRenderContext renderContext, UnityEngine.Camera[] cameras) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/RenderPipeline/HDRenderPipeline.cs:1566)
UnityEngine.Rendering.RenderPipeline.InternalRender (UnityEngine.Rendering.ScriptableRenderContext context, UnityEngine.Camera[] cameras) (at <2e6610ed29844f85a37924f81509fe5d>:0)
UnityEngine.Rendering.RenderPipelineManager.DoRenderLoop_Internal (UnityEngine.Rendering.RenderPipelineAsset pipe, System.IntPtr loopPtr, Unity.Collections.LowLevel.Unsafe.AtomicSafetyHandle safety) (at <2e6610ed29844f85a37924f81509fe5d>:0)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&)
NullReferenceException: Object reference not set to an instance of an object
UnityEngine.Rendering.HighDefinition.HDRISkyRenderer.RenderSky (UnityEngine.Rendering.HighDefinition.BuiltinSkyParameters builtinParams, System.Boolean renderForCubemap, System.Boolean renderSunDisk) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/Sky/HDRISky/HDRISkyRenderer.cs:155)
UnityEngine.Rendering.HighDefinition.SkyManager.RenderSkyToCubemap (UnityEngine.Rendering.HighDefinition.SkyUpdateContext skyContext) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/Sky/SkyManager.cs:501)
UnityEngine.Rendering.HighDefinition.SkyManager.UpdateEnvironment (UnityEngine.Rendering.HighDefinition.HDCamera hdCamera, UnityEngine.Rendering.ScriptableRenderContext renderContext, UnityEngine.Rendering.HighDefinition.SkyUpdateContext skyContext, UnityEngine.Light sunLight, System.Boolean updateRequired, System.Boolean updateAmbientProbe, System.Boolean staticSky, UnityEngine.Rendering.HighDefinition.SkyAmbientMode ambientMode, System.Int32 frameIndex, UnityEngine.Rendering.CommandBuffer cmd) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/Sky/SkyManager.cs:748)
UnityEngine.Rendering.HighDefinition.SkyManager.UpdateEnvironment (UnityEngine.Rendering.HighDefinition.HDCamera hdCamera, UnityEngine.Rendering.ScriptableRenderContext renderContext, UnityEngine.Light sunLight, System.Int32 frameIndex, UnityEngine.Rendering.CommandBuffer cmd) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/Sky/SkyManager.cs:809)
UnityEngine.Rendering.HighDefinition.HDRenderPipeline.UpdateSkyEnvironment (UnityEngine.Rendering.HighDefinition.HDCamera hdCamera, UnityEngine.Rendering.ScriptableRenderContext renderContext, System.Int32 frameIndex, UnityEngine.Rendering.CommandBuffer cmd) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/RenderPipeline/HDRenderPipeline.cs:3733)
UnityEngine.Rendering.HighDefinition.HDRenderPipeline.ExecuteRenderRequest (UnityEngine.Rendering.HighDefinition.HDRenderPipeline+RenderRequest renderRequest, UnityEngine.Rendering.ScriptableRenderContext renderContext, UnityEngine.Rendering.CommandBuffer cmd, UnityEngine.Rendering.HighDefinition.AOVRequestData aovRequest) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/RenderPipeline/HDRenderPipeline.cs:2237)
UnityEngine.Rendering.HighDefinition.HDRenderPipeline.Render (UnityEngine.Rendering.ScriptableRenderContext renderContext, UnityEngine.Camera[] cameras) (at Library/PackageCache/com.unity.render-pipelines.high-definition@9.0.0-preview.33/Runtime/RenderPipeline/HDRenderPipeline.cs:2039)
UnityEngine.Rendering.RenderPipeline.InternalRender (UnityEngine.Rendering.ScriptableRenderContext context, UnityEngine.Camera[] cameras) (at <2e6610ed29844f85a37924f81509fe5d>:0)
UnityEngine.Rendering.RenderPipelineManager.DoRenderLoop_Internal (UnityEngine.Rendering.RenderPipelineAsset pipe, System.IntPtr loopPtr, Unity.Collections.LowLevel.Unsafe.AtomicSafetyHandle safety) (at <2e6610ed29844f85a37924f81509fe5d>:0)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&)