HDMI audio on Optimus laptop with Turing card


I have an Optimus laptop HP Zbook 15 G6, which has an Nvidia Quadro T1000 card. I am trying to get the HDMI audio output to work, but unfortunately no luck. I have the graphics setup in hybrid PRIME offload mode (through mhwd) and that all works fine (with prime-run). However, when I connect an external TV, I see the desktop on it, but cannot redirect audio to it. There is no HDMI audio card in pulseaudio detected. I have tried it through nvhda, but no luck. I also cannot see the audio device in lspci output (only NVIDIA GPU card). However, in lspci tree, I see that there is a 01.00.1 subtree of the NVIDIA card, so the audio must be there. I have also tried it with the pci device rescan during boot, but no luck. Any idea?

Just to inform on the progress - it might help someone. I have discovered that when I turn off the NVIDIA card in the BIOS of the system, the HDMI audio output is “switched” to the internal Intel GPU, so it works normally as if there was no NVIDIA card. With only iGPU I can plug-in the external monitor and I automatically get HDMI audio. So that is one possibility: for normal work and stuff keep only iGPU in BIOS and then for Nvidia stuff reboot and turn Nvidia on. I have installed the hybrid 450 prime offloading package via mhwd and it doesn’t seem to care whether the BIOS has only iGPU or both: when I have both, prime-run works, when only iGPU, prime-run doesn’t work, which is all fine. However, I realize that if I would be able to install driver 450 with Bumblebee, I wouldn’t need a restart, because bbswitch keeps the dGPU powered down (and not on all the time like Nvidia PRIME offloading does). In case of Bumblebee I could have HDMI with iGPU AND possibility to turn on NVIDIA whenever I like. Now a question: IS there a possibility to somehow install Bumblebee with Nvidia driver 450? I don’t see that option in MHWD…