Latest Plex, version 1.2.7.2987-1bef33a_amd64
Similar issues:
https://forums.plex.tv/discussion/242526/pms-1-1-4-fails-to-start-on-ubuntu-16-04
https://forums.plex.tv/discussion/228947/ubuntu-16-04-1-plexmediaserver-1-1-0-2611-installation-systemd-config-issues
I've tried the instructions in those posts, and elsewhere on the internet, but I keep getting the same issue. I'm pretty familiar with Linux, if you need any more detailed info. This is very frustrating, I'm almost considering downgrading my distro.