I have a script for you which should fix this once and for all.
- Control Panel - Scheduled Tasks - User Script
- It runs as ‘root’
- It emails you the output
- Task Settings (the actual script) are:
#!/bin/bash
PlexShare="$(synoshare --get Plex | grep Path | sed -e 's/.*\[//' | sed -e 's/\]//')"
echo Plex shared folder is at: \"$PlexShare\"
synoacltool -del "$PlexShare"
synoacltool -add "$PlexShare" group:administrators:allow:rwxpdDaARWc--:fd--
synoacltool -add "$PlexShare" user:admin:allow:rwxpdDaARWc:fd--
synoacltool -add "$PlexShare" user:PlexMediaServer:allow:rwxpdDaARWcCo:fd--
Save this task,
Run it once,
Verify you now have Full Control for System Internal User “PlexMediaServer”
You can post here what it sends you if you wish / have issues.