Seems like the same as: Server doesn't restart after 1.15.6.1079 update
Can you please try my suggestion there? tl;dr:
service plexmediaserver-plexpass stop
pkg remove plexmediaserver-plexpass
rm -rf /usr/local/share/plexmediaserver-plexpass
pkg install /usr/local/share/plexmediaserver-plexpass
service plexmediaserver-plexpass start
does that fix it?
