I am using File System sync to a folder on a 2nd drive on my linux pop_os. The path is /media/mpt/drive2/MegaSync/Google Pixel/Joplin
This path is synced to my android using syncthing.
The problem is that Joplin doesn't seem to "see" the folder. No notes show up in the Joplin app.
After days of troubleshooting the key insight is that if I change the Joplin folder to my main drive it works. But if I change the folder to any folder on my 2nd drive it it doesn't show up in Joplin. There are no error messages.
What I mean is that Joplin just shows empty database when the sync target (in settings) is any location on "drive 2". (Though the Joplin database is there).
If I move my Joplin folder to any folder on drive 1 (the drive/disk that the OS is installed on) then Joplin loads my database successfully and it will sync.
So, to summarize, my problem isn't syncing, it is that if my Jopin data folder is located on my Drive 2, then it can't read/load it.
I did another test that confirmed my suspicion - I tried dragging an attachments (image file) that is stored on Drive 2 into Joplin and I get the message that the path cannot be accessed.
For the record every other program has no problem accessing the path.