Here is an ugly workaround to fix it.
Change User and Group to root
in the service file plexmediaserver.service
.
sudo nano /usr/lib/systemd/system/plexmediaserver.service
Example:
[Unit]
Description=Plex Media Server
After=network.target
[Service]
EnvironmentFile=/etc/conf.d/plexmediaserver
ExecStart=/usr/lib/plexmediaserver/Plex\x20Media\x20Server
Type=simple
User=root
Group=root
Restart=on-failure
RestartSec=5
StartLimitInterval=60s
StartLimitBurst=3
[Install]
WantedBy=multi-user.target
Then restart the service.
systemctl daemon-reload
sudo systemctl restart plexmediaserver.service