We have an extensive hierarchic category structure, and I've just noticed that the URLs for only the bottom-level child categories get rewritten into the permalink format.
For example, domain.org/?cat=121 gets rewritten to domain.org/category/locations/africa/nigeria/ (as desired). But domain.org/?cat=5 (africa) does not get rewritten.
Besides presenting "nonpretty" URLs, this prevents some custom functions from working on parent-level categories.
How can I fix this, that is?