Create & Read from AppendStructuredBuffer<>

Development Programming & Scripting C++
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How to pass AppendStructuredBuffer<> to my compute shader & read it back (or, after dispatch, convert to StructuredBuffer for another shader to pass directly without reading back in CPU)?

Here is what I’ve achieved so far:

class My_CS : FGlobalShader 
  ... 
  SHADER_PARAMETER_UAV(AppendStructuredBuffer<float3>, appendParam)
  ...

Dispatching shader:

...
FRHIResourceCreateInfo Info(TEXT("appendParam"));
   			FBufferRHIRef Buffer = RHICreateStructuredBuffer(sizeof(float3), sizeof(float3) , BUF_UnorderedAccess | BUF_ShaderResource, ERHIAccess::UAVMask, Info);
...

My_CS::FParameters params;
params.appendBuffer = RHICreateUnorderedAccessView(Buffer, false, true);

FComputeShaderUtils::Dispatch( ....

compute shader for append:

...
AppendStructuredBuffer<float3> appendParam;

[numthreads(N, N, N)]
void MainFrustumCullShader(uint3 GroupId : SV_GroupID)
{
    float3 data = ... read data from ...
    appendParam.Append(data);
}

I can pass RWStructuredBuffer<> to compute shader & read back in CPU or pass to antoher compute shader directly. But AppendStructuredBuffer seems to have no data and no error/crash is thrown when executing

Thanks!