In my starting position (SLES12, kernel-default-3.12.39-47.1.s390x, grub2-2.02~beta2-48.3.s390x) the grub behavior was as expected.
After upgrading the system to kernel-default-3.12.43-52.6.1.s390x with grub2-2.02~beta2-54.1.s390x the boot process stops with the grub promt.
Any attempts in changing the /etc/defaults/grub and downgrading to the previous grub were not successfully. Is the any chance to get the cause and to fix it?