ksh as login shell for root: unexpected behaviour

Coming from Solaris 10 with the korn shell as root's default shell, I intend to do the same on RHEL 7.4. However, after chsh'ing to /bin/ksh, a login on the (VMWare provided) console leads to Problems. It seems as if the Login process spawns a ksh process which itself spawns another ksh instance, presuambly the cause for the "you have running Jobs" message when trying to reboot the VM by issuing "init 6". A reboot lasts some 30 seconds in this case while using bash, the machine restarts right away. Issuing another "Init 6" while waiting throws some "Unregistered something" reror Messages.

Frankly, I am confused. Using bash as Default Shell is a fallback I am willing to accept, but since I have found nothing on the Internet so far, I was wondering if anyone has managed to accomplish the Task.

Happened on a minimal Installation and a infrastructure Server Environment aswell. In both cases, the base Environment and a few more packages including ksh were installed via anaconda using a kickstart file.