JAnD added a comment.
Some more investigating:
interwiki category:Foo - recognizes
interwki -start:Category:Bar - not always recognizes
TASK DETAIL
https://phabricator.wikimedia.org/T87222
EMAIL PREFERENCES
https://phabricator.wikimedia.org/settings/panel/emailpreferences/
To: JAnD
Cc: Mpaa, Aklapper, JAnD, jayvdb, pywikipedia-bugs