Avatars are tied into the premium tier memberships. I think it was broken for a little while after we moved to the new software, so that may have been when you changed it. But the permission is a little weird -- it's not permission to *have* an avatar, it's permission to *change* your avatar.
Let me know if you want to get rid of your current one or change it to something else. I can probably fix it on the back end.