DEBUG log files which capture this issue are needed.
It is impossible to diagnose based on description.
You should consider making a permanent mount location and not relying on the automounter. The automounter changes master permissions and will deny user plex from seeing the media in spite of actual file permissions.
If a USB device, use the UUID= method to identify the drive else use the fixed internal (/dev/sdxn) method.
Options are very simple.
a. UUID value from sudo blkid /dev/sdxx
b. auto mount
c. Don’t fail if not plugged in
d. Background if not yet ready (so it will mount as soon as it is ready)
Just so it’s clear – Neither is officially supported.
That means; If you run into quirks and things which can’t be explained, I will , suggest what I think it is, then wish you the best.
Those “derivatives” of Debian/Ubuntu always leave something out. Sometimes, like Mint, they leave out a lot of stability and needed base functionality in their kernel builds
I have changed fstab but the problem is remain the same.
So I have decided to look in the logs and I ran update metadata and spotted error came up with
/var/lib/plexmediaserver/Library/Application Support/Plex Media Server/
Permission denied.
I checked and found some plex:plex and some root:root. So the path unable to update due to access denied. (I guess it becauss i moved from old server on ntfs hard drive then move on to new one so the ntfs change own and group to root:root.
I have change ownership and grup to plex on all of those folder using sudo chown -R plex /var/lib/plexmediaserver/Library/Application Support/Plex Media Server/*
Same goes for chgrp.
Then I ran update metadata and it works update it all and the path is now correct, no more error of transcoder.