No it doesnt appear under
/volumes. I hadnt considered that, however I dont know if thats really the issue.
I got to thinking about this yesterday and realized that when you set a custom icon for a drive on MacOS it places a hidden
.VolumeIcon file at the root. Seafile requires you to use Libraries to store data, and you cannot put files at the root level. So I would imagine when they created Seadrive they took this into account and put things in place to prevent users from placing files at the root level. This seems to explain why I had to enter my admin password and then nothing happened.
But I did find a workaround. I created a Symlink to my Seafile Drive folder, placed the Symlink on my desktop, changed its icon. Tthis does leave the original Seadrive Icon on the desktop too, But Since I use the MacOS Stickies app I just hid the original icon behind a sticky note