It is not helping to create a new virtual server and trying to install from scratch.
I have installed NethServer 7.7.1908 more than once and on ESXi, VirtualBox. All probably were using MBR boot. I never touched Installation Destination as it was always auto set.
This is the first time I am trying to install on an EFI boot and having problem.
Is there a way to see log files of the installer? I might find something there, hopefully.
BTW, this is Windows 10 pro host with Hyper-V manager version 10.0.18362.1, Virtual Server having Configuration version 9.0. Moreover, it is also not helping to have Secure boot feature enabled or disabled. Not sure if that will be of any help though.