bUsePrecompiled does not work, cannot be found?

I wanna hide some source code of my plugin, so I try to use bUsePrecompiled = true to skip step by using the precompiled cpp data.
However, weird error occurred.
I swear it compile correctly without adding bUsePrecompiled = true in build.cs.

         ?? UnrealBuildTool.UnrealBuildTool.Main(String[] ArgumentsArray) λ?? D:\Build\++UE4\Sync\Engine\Saved\CsTools\Engine\Source\Programs\UnrealBuildTool\UnrealBuildTool.cs:?к? 443
Creating makefile for MyProject123Editor (ini files are newer than makefile)
ERROR: Unhandled exception: System.Collections.Generic.KeyNotFoundException: ?????ؼ??ֲ????ֵ??С?
          ?? System.ThrowHelper.ThrowKeyNotFoundException()
          ?? System.Collections.Generic.Dictionary`2.get_Item(TKey key)
          ?? UnrealBuildTool.HotReload.ApplyState(HotReloadState HotReloadState, TargetMakefile Makefile) λ?? D:\Build\++UE4\Sync\Engine\Saved\CsTools\Engine\Source\Programs\UnrealBuildTool\System\HotReload.cs:?к? 320
          ?? UnrealBuildTool.BuildMode.GetActionsForTarget(BuildConfiguration BuildConfiguration, TargetDescriptor TargetDescriptor, TargetMakefile Makefile) λ?? D:\Build\++UE4\Sync\Engine\Saved\CsTools\Engine\Source\Programs\UnrealBuildTool\Modes\BuildMode.cs:?к? 532
          ?? UnrealBuildTool.BuildMode.Build(List`1 TargetDescriptors, BuildConfiguration BuildConfiguration, ISourceFileWorkingSet WorkingSet, BuildOptions Options) λ?? D:\Build\++UE4\Sync\Engine\Saved\CsTools\Engine\Source\Programs\UnrealBuildTool\Modes\BuildMode.cs:?к? 242
          ?? UnrealBuildTool.BuildMode.Execute(CommandLineArguments Arguments) λ?? D:\Build\++UE4\Sync\Engine\Saved\CsTools\Engine\Source\Programs\UnrealBuildTool\Modes\BuildMode.cs:?к? 191

No idea, it just disappeared.

have you resolve it ? I have a same issue.