I'm testing the Kali 2019.1 LXDE ISO. I wrote the ISO image to a blank DVD and booted from that.

There are problems with both shutdown and rebooting which seem to arise because the disc is ejected prematurely. There are many error messages indicating attempted disc access after it is ejected. The shutdown process hangs eventually. The reboot process does occur, but only after some script times out.

The problem might not occur if booting from USB flash drive as opposed to DVD (since those aren't removable media). But it might happen if you write the Kali ISO to an SD card and boot from a USB card reader (since the reader might support the eject command).

However, sometimes on selecting shut down, the disc is not ejected and the PC powers off almost immediately. I can hear the DVD drive slowly spinning down after power is cut. I don't know whether an eject command (i.e. START STOP UNIT) is issued or not, but the system certainly isn't waiting for it to complete.

I'm not sure what determines whether a shutdown is "successful" (but without ejecting) vs ejecting then hanging after lots of error messages. Perhaps it depends on whether required data is in the page cache? If so, doing

echo 3 >/proc/sys/vm/drop_caches

before selecting Shutdown could help to reliably reproduce this issue.