A few days ago I have updated this forum from Discourse 1.2.0.beta5 to 1.2.0.beta6. It is possible that this might cause or has caused some minor issues. Please report in here if some feature that’s supposed to work doesn’t function.
In particular, I suspect that there are some issues with uploading avatars. If it doesn’t work for you, it’s probably a bug from the new version.
Edit: I rebuilt the forum. This seemed to have solved at least the issue with the broken avatars.