I have too had this issue and it is related to when the system trys to jump to using a gui beet screen.
I had this same problem on 3.18 and 4.0.2 and solved it by doing the following
edit /etc/default/grub
change
GRUB_CMDLINE_LINUX=“rhgb quiet crashkernel=auto”
to
GRUB_CMDLINE_LINUX=“crashkernel=auto”
Then run
grub2-mkconfig -o /boot/grub2/grub.cfg
I would suggest making this a change to the distro as it seems to be causing a few issues and there is no need for the gui boot screen on a server?
Cheers
Chris