Some graphic drivers renders console unusable after kexec. From image version 3.4.4 all KMS drivers were removed and kernel uses the default VGA 80x25 mode. Frozen console or graphic artifacts can be solved by choosing a different driver when using virtualization or selecting older hardware emulation version (VMWare version 4 or 5). When reporting graphic driver issues, attach “lsmod” output from discovered nodes and try to blacklist “kms” drivers as a workaround.
with the foreman-discovery-image version prior 3.4.4 it works.