Just read this thread as I have the same issue. I created the group on an Android phone using message+, I have all members of the group in my contacts as do all of them. Some (most) of the members are iPhone users. I see all of their names on my device, as they are in my contacts, as expected; they only see phone numbers. Each of the iPhone users have successfully used the #NAME trick. However, they only see my posts as my phone number. This seems to be an Android vs iOS issue. Irritating and frustrating.