There is a general feature/bug/behavior that template-inserted categories don't update until there's a null edit or better, as a rule. This impression seems confirmed to me by my reading of
This behavior is interfering with the proper functioning of the WP:BLPPROD maintenance process.
I have been told by a knowledgable user (as I've been pursuing a BRFA for a bot
to deal with the trouble this is causing a single particular maintenance
category at ENWIKI) that this relates to purge, etc., not updating the
See also: https://bugzilla.wikimedia.org/show_bug.cgi?id=31628, http://sourceforge.net/tracker/index.php?func=detail&aid=970584&group_id=34373&atid=411192, and possibly https://bugzilla.wikimedia.org/show_bug.cgi?id=4857