But report:
In my attempts to have non-generic icons to my oneshots, I found a solution - I copy existing oneshots with icons to the soundset, then change them, delete the existing playlist and place my own music.
However, once I copy oneshots, the icons of ALL the oneshots changes to the one I copied last for no apparent reason.
This seems to be a bug. It happens to ALL oneshots, even ones I copied that had other icons.