Ubuntu 16.04 boots to command line despite settings

I have an oldish Ubuntu 16.04.05 LTS running in VirtualBox (Windows 10 host). For some reason it boots always to command line even though it should start in GUI. That is, systemctl get-default reports graphical.target, lightdm.service is enabled (or not sure since this is still a jumble of systemd and SysV init but seems to be) and right after boot also systemctl status graphical.target says it was reached. journalctl doesn't report any issues. GUI starts without issue with systemctl start lightdm.service or also with just /etc/init.d/lightdm start.

I may have done this myself somehow since I had some issues with the virtual machine at some point but can't remember what I did.