Hello, I have the same issue and didn't find any help on the matter.
Does someone have an idea?
[Edit] It seems to be an issue for all types of nested virtualization on windows. I tried to install Hyper-V feature on these OS:
Windows 10 Pro
Windows Server 2016
Windows Server 2019 Datacenter Edition
Fully updated, including drivers.
But always same BSOD when restarting the VM to finish installing Hyper-V: "hypervisor error"...
However, an ESXI will allow running multiple VMs simultaneously! But these VMs doesn't work properly though, I cannot run Windows update (always an error after a few minutes) neither installing applications (nothing append after allowing system modification). But at least VMs are running!
If it can help, I run my Unraid (v6.8.3) on a 1950x AMD CPU / Gigabyte x399 Aorus pro