During some testing to determine how avatars are scaled, etc. I also uploaded an image which was 192x96px.
In both cases I am now unable to set the crop position using the Avatar Editor.
The Avatar Editor overlay stays open and when I click close, the position resets.
This only seems to occur with images which are exactly 384x192 or 192x96.
I was able to upload an image of 768x384 and was able to set the crop position successfully.