I have no issue setting custom icons for other drives, but when I try to set a custom icon for Seafile Drive I get asked for my admin password and then nothing happens.
Anyone know what I can do to fix this? Kind of bummed out, I just spent 4 hours designing my own custom icon.
SeaDrive isn’t actually a Volume on macOS, is it? Do you see it listed under /Volumes? I don’t think it will take a drive icon in the standard fashion for that reason.
Is there an alternate location for a drive icon?
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 
Seems to me that the simplest (maybe most simple-minded) way to customize a drive icon is to place a .VolumeIcon file at the root level of the disk.
I cannot write anything to the root level of SeaDrive, however. In contrast, I can add a .VolumeIcon image to the root level of a USB flash drive.