I have the same issue. @Keliaxx, were you able to resolve this? It seems proxmox has it resolved their kernel but I am not sure how that relates to unraid's.
https://forum.proxmox.com/threads/amd-nested-virtualization-not-working-after-7-1-upgrade.100072/
@indy1250 any luck? I was only able to get to the "TianoCore" bios and then it's stuck without booting into windows.
@hot22shot I added the qemu parameters to the XML
EDIT:
i got the video card work. I changed the boot order to have windows iso installation as 1 and my main hdd as 2. I let the "press any key to install windows" timeout and then it booted into windows. *go figure*