D2R does not launch (NVSDK_NGX_D3D12_Init failed?)

So Nahimic is just one of a number of different programs that when experiencing issues can affect various games/services. Anything that can take control of hardware can do this. The dxdiag you provided didn’t include any errors and it wont tell us what programs are running on the system. However I did notice the GPU drivers are significantly out of date.

Try updating them either through Geforce Experience or by this direct link: Geforce Driver Results | NVIDIA (desktop) or Geforce Driver Results | NVIDIA (notebook)

Also check any other drivers for audio, network or motherboard from the maker of that hardware.

If you can post the error section from your dxdiag txt file that may also help us figure out the source of the conflict.