image version 3.4.4 is out, we have found that 3.4.x images were missing EFI bootloaders due to regression introduced in RHEL 7.4 grub2 subpackages. This has been fixed now. One additional error was fixed in this version: Bug #22112: Discovery image unable to configure network via DHCP on the first attempt - Discovery - Foreman
Download now at: http://downloads.theforeman.org/discovery/releases/3.4/
The image is Foreman 1.15 - 1.17 compatible. Have fun!
Your Foreman Discovery team.