I'm trying to convert a Windows server 2012r2 server running on ESXi 5.1 to Hyper-V. I started out using the MS virtual machine converter, but it doesn't seem to support UEFI machines. I found this 5NINE's tool, which seems good I have been able to convert a couple of machines, but now I have one that I just can't convert. I get a message:

"failed to convert virtual machine 'hostname'. Failed to provision a new virtual machine. I end up with a ~25GB vhdx, the source machine has a 40GB HDD. I believe part of the problem is that the conversion wizard has Generation 1 auto selected, and greyed out. I can't change it to Gen 2. The source VM has SCSI disk and EFI 'bios', so I know Gen 1 Hyper V machine won't work. Why will this tool not allow me to select Gen 2? I tried other VMs, same source host, all deployed from same base template, and they show up as Gen 2. I can't figure this out and really don't want to have to rebuild this machine

Can anyone assist?