I've just noticed, in the ToC editor, if I delete an item, it'll automatically delete all sub-items. I feel like this is new behaviour, and it doesn't seem ideal, at least for me.
As an example, if I have a ToC like:
If I delete Part 2, it'll nuke Chapters 3 and 4 along with it, whereas previously it wouldn't affect them. It would be nice if it could either leave the subheaders alone, or have the option to do either.