Changing category parent

I had a couple of top-level categories that I decided to make sub-categories. I edited them both and changed the parent, and at the same time changed the description, but not the SLUG. They show up fine on the category maintenance screen as children of the top-level category, but they no longer show up on the sidebar (using list_cats()). And they no longer show up as options on the post edit screen. Can anyone help me work out why?