Error adding HyperV feature on Server 2016

Attempting to add the Hyper-V feature to a fresh Server 2016 VM. I receive the message:

"Hyper-V cannot be installed because virtualization support is not enabled in the BIOS"

After picking through some very limited search results I attempted to modify the VM using "cpu_passthrough=true", however the error remains.

Any advice to get this working? Thanks

Andy