@chief I tried with a windows 10 build 1703 install and it booted just fine. Still not sure where things go wrong here but as we seem to have several people with this we should be able to figure this out.
Please edit /var/www/fog/service/ipxe/refind.conf. Change timeout to zero. Save this, change EFI exit type to rEFInd and boot the client. You should see a boot selection menu. Do you see it or does it hang even before that?