Hi
I created an installation with KVM but I can never connect to a network interface, the same happens if I install debian or tails in kvm.
i used gnome boxes and it works for me at least debian and tails, but I think whonix is not supported here
Then the only realistic way to resolve this issue is thorough Self Support First Policy for Whonix.
Note: I am not a maintainer for Whonix KVM.