This is intentional, the autosave content clears on submit. I know that's a bit of an annoying situation, but this would be so rare that we're not going to re-engineer the way autosaves works for such a unique circumstance. In fact, I can't even think how we would even do that.
I can't reproduce this... What model are you using? Does it happen on every topic? @bfarber Can you reproduce both locally and here? I can probably help with the editor better than Rikki, but it was you that added that invisible character and I can't see the old report... does the problem still happen if you take that out?