Board Thread:General Coding Help/@comment-33008805-20171016233832/@comment-24757753-20171027071252

It looks like Wikia have recently created a new  API query list for listing users who are members of a particular group, and are removing that (and some other) functionality from the   query list your example uses.

Once it's available (next week, I guess, since it's been merged), it might be worth testing to see if this new query list works as you wish.