How to Copy an UAV Texture to the MobileSceneColor RenderTarget?

Development Rendering
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I 'm trying to Copy an UAV Texture to the render target of Mobile forward pipleline:

TRefCountPtr<IPooledRenderTarget> MyOutput = nullptr;

//custome shader, the .usf code just simply make the input UAV red
class MyCS : public FGlobalShader
{
	DECLARE_SHADER_TYPE(MyCS, Global);
	SHADER_USE_PARAMETER_STRUCT(MyCS, FGlobalShader);

public:
	// The number of texels on each axis processed by a single thread group.
	static const FIntPoint TexelsPerThreadGroup;

	static const uint32 ThreadGroupSizeX = 16;
	static const uint32 ThreadGroupSizeY = 16;

	static bool ShouldCompilePermutation(const FGlobalShaderPermutationParameters& Parameters)
	{
		return IsMobilePlatform(Parameters.Platform);
	}

	static void ModifyCompilationEnvironment(const FGlobalShaderPermutationParameters& Parameters, FShaderCompilerEnvironment& OutEnvironment)
	{
		OutEnvironment.SetDefine(TEXT("THREADGROUP_SIZEX"), ThreadGroupSizeX);
		OutEnvironment.SetDefine(TEXT("THREADGROUP_SIZEY"), ThreadGroupSizeY);
	}

	BEGIN_SHADER_PARAMETER_STRUCT(FParameters, )
		SHADER_PARAMETER_RDG_TEXTURE_UAV(RWTexture2D<float4>, OutputTexture)
	END_SHADER_PARAMETER_STRUCT()
};
const FIntPoint MyCS::TexelsPerThreadGroup(ThreadGroupSizeX, ThreadGroupSizeY);
IMPLEMENT_SHADER_TYPE(, MyCS, TEXT("/Engine/Private/MyCS.usf"), TEXT("mainCS"), SF_Compute);

//Function used to add my pass and setup shaderparameters
void FMobileSceneRenderer::MyPass(FRHICommandListImmediate& RHICmdList, FRDGBuilder& GraphBuilder, const FViewInfo& View, TRefCountPtr<IPooledRenderTarget>& OutputTexture) {

	TShaderMapRef<MyCS> ComputeShader(View.ShaderMap);

	MyCS::FParameters* CSShaderParameters = GraphBuilder.AllocParameters<MyCS::FParameters>();

	FRDGTextureRef Output = GraphBuilder.CreateTexture(FRDGTextureDesc::Create2DDesc(
		OutputTexture->GetDesc().Extent,
		OutputTexture->GetDesc().Format,
		OutputTexture->GetDesc().ClearValue,
		OutputTexture->GetDesc().Flags,
		OutputTexture->GetDesc().TargetableFlags | TexCreate_UAV,
		false),
		TEXT("MyOutput"));

	CSShaderParameters->OutputTexture = GraphBuilder.CreateUAV(Output);

	FComputeShaderUtils::AddPass(
		GraphBuilder,
		RDG_EVENT_NAME("MyPass(CS)"),
		ERDGPassFlags::Compute,
		ComputeShader,
		CSShaderParameters,
		FComputeShaderUtils::GetGroupCount(View.ViewRect.Size(), 
                MyCS::TexelsPerThreadGroup)
	);

	GraphBuilder.QueueTextureExtraction(Output, &OutputTexture);
};

//And finally I add my pass after the SceneColorRendering pass is done
FRHITexture* FMobileSceneRenderer::RenderForward(FRHICommandListImmediate& RHICmdList, const TArrayView<const FViewInfo*> ViewList){

    //...unrelated code.../

    FPooledRenderTargetDesc DescOut = SceneContext.GetSceneColor()->GetDesc();
    if (!MyOutput.GetReference()) {
        GRenderTargetPool.FindFreeElement(RHICmdList, DescOut, MyOutput, 
         TEXT("MyOutput"));
    }

    //...unrelated code.../

    FRDGBuilder GraphBuilder(RHICmdList);
    MyPass(RHICmdList, GraphBuilder, View, MyOutput); 
    GraphBuilder.Execute();
    
     RHICmdList.EndRenderPass();

    //Copy 
    //SceneColor is the rendertarget used in the RenderPassInfo
    FRHICopyTextureInfo CopyInfo;
    RHICmdList.CopyTexture(MyOutput->GetRenderTargetItem().TargetableTexture, SceneColor, 
    CopyInfo);

    return SceneColorResolve ? SceneColorResolve : SceneColor;
}

I have captured a frame in RenderDoc and found the copy call as showed below:
1652181644(1)
1652181713(1)
But the output is not as expected (it should be red in my expection), it’s just how it look likes before doing the copy:
1652181768(1)
Does anyone have solusions? Many thanks :smiley: