Odd bug with bullet (and possibly ordered) lists, using BBCode.
Try creating a bullet list; I used the format [ list], with each item marked by [ *] (you don't have to use [ li] and [ /li]). In the following text, if you happen to include an extra [ /list] command, you can't ever delete it when editing, unless you delete all the offending text and start over. In fact, if you add another [ /list] command, THAT one will persist, as well. In fact, this bug extends to the initial [ list]. If you cut, then paste the text back in without the extra tags, however, this problem goes away (until accidentally you type an extra list tag again, that is).
AFAIK, this problem only happens when editing already-posted content, not the initial post.
I've been able to repeat this problem over and over, since I discovered it a moment ago, including after refreshing the page and a reboot.