There are many threads that ask why hiking does not count towards walking and previously the answer would be, that they're different categories and that users might as well use walking to have their hikes count towards walking badges and challenges.
Well, now there are hiking badges (the 1000m ascend Garmin Connect+ badges) as well and I still don't see sense in not having hiking count towards walking badges and challenges.
Garmin, please, at least consider accepting hiking activities for walking badges/challenges progress.