More info needed. How are you running Jellyfin? How is the drive attached? What OS?

Ok so the issue was it not being mounted corrected but it’s been fixed and I’ve tested it on a number of devices and I can confirm it’s working now only took me over a year 2 different OS and 3 different devices to get Jellyfin working (which will admit was due to user error)

Add your disk to fstab, and make sure jellyfin user has access to it. Mint may have a GUI tool Disks to manage disks, but reading the Arch wiki article is a good idea.

https://wiki.archlinux.org/title/Fstab

Can you browse to the files via the mount point? Is the external drive listed at all?

From there you want to make sure you have the location listed as the library location in jellyfin. Then make sure the naming/file structure is correct according to the jellyfin documentation.