AV1 encoder initialization fails with status code 8

I would like to use the AV1 encoder of the video codec SDK but am having trouble to correctly instantiate it. At first I thought this was a problem with my implementation, but I can reproduce this with the AppEnc* application in the Samples suite of the video codec SDK 12.2.

To do so, build the sample suite, and run, for example, AppEncD3D12.exe [-i ...] [-s ...] -codec av1 and you will get: NvEncoder::CreateEncoder : m_nvenc.nvEncInitializeEncoder(m_hEncoder, &m_initializeParams) returned error 8. What is the cause here?

While debugging, I followed the instructions to set up the NV_ENC_INITIALIZE_PARAMS structure with the most basic settings (and set the encodeConfig member to NULL as recommended in the documentation to use the default settings) with the same result: error 8. I have been unable to initialize any AV1 encoder so far.

H264 and HEVC work without any problems. Hardware is an RTX 4500, SDK version 12.2 on Windows.

Is there any update to this? I’m using PynvVideoCodec, which I know is based on the SDK, and seeing a similar issue.

RuntimeError: Failed to get preset configuration. Error code 8

Edit:
Oops. I looked at the pinned post on compatibility and it seems AV1 is unsupported for my GPU. Hardware is RTX A6000 on Ubuntu.