Using NTFS/Fat32 formatted HDD needed to be mounted properly on Linux.
This are steps for plex to read the directory:
df -h
find out which /dev is the external hdd, for example is /dev/sdb2
sudo umount /dev/sdb2
sudo mkdir -p /mnt/exthdd
sudo mount -t ntfs -o defaults,uid=999,gid=1000 /dev/sdb2 /mnt/exthdd
This will TEMPORARILY mount your NTFS external hard drive. It will only work until you reboot your PC. To mount your hard drive long term you will have to follow the steps below:
The next and final step will mount your NTFS hard drive to the “mnt” directory found in “File System”. Your hard drive will be located there after a reboot from then on.
sudo nano /etc/fstab
*then type the following below*
/dev/sdb2 /mnt/exthdd ntfs defaults,uid=999,gid=1000 0 0
*then save and exit by pressing (CTRL+X)*