Nvidia's VXGI2-4.21 + PixelStreaming triggers "Failed to register input back buffer"

I’m trying to use nvidia’s vxgi2-4.21 with pixel streaming and get this exception.

Any thoughts on what’s going on there and if it’s at all doable would be much appreciated.
It’s in NvVideoEncoder.cpp

It’s the dx 12.

I have the same error with 4.21 vxgi. Port all the project in 4.22 preview. Work very well in local, but i notice that there isnt ray tracing.
So i add the argument -dx12 to start the exe like you need to use raytracing in the editor end get same error.

Sorry for my english.