Steps:
Create a Windows 11 64-bit VM and save
Error - "The UEFI NVRAM file is not existing for this machine"
VM settings become inaccessible
Workaround - start and stop the VM once using VBoxManage
VBoxManage stratvm --type=headless <vmname>
VBoxManage controlvm <vmname> poweroff
.nvram file should be created in the VM directory.