Over the last several days I noticed that drafts show up as saved down at the bottom but when I click the link it takes me to the thread at the very top and when I scroll to the bottom the draft is not there at all.
I have this happen a lot. I have come to conclude it is because they are over 6 hours old. It seems to save them for the 6 hours but once that time passes the link will remain but the post itself will go clear. It won't vanish for me until I actually post in the topic/tab again or hit the clear button.