Collapsing Categories Plugin problem

I’m using the Collapsing Categories plugin by Robert Felty, but I’ve been having a weird problem with it lately. The categories are clickable and expandable, but sometimes a category will link to the parent category instead of the category.

For example, Resource Directory has 3 children categories, Ceilings, Walls, and Floors. Ceilings and Walls each link to their own category page, but Floors links back to Resource Directory.

When I fiddle with Floors (un-child it, then put it back), Floors links to Floors properly, but then Old-House Journal, a child category of Articles, starts linking to Articles instead of Old-House Journal.

What is going on here and how do I fix this mayhem?