I have added a post category ancestor location rule to my filters and functions, not exactly a parent category rule, but it does the same thing. It will not match on the category so if you want it to match the category or any of its decedents then you need to set up both in the location rules. Hope this helps. https://github.com/Hube2/acf-filters-and-functions/blob/master/acf-post-category-ancestor-location-rule.php
