Not getting Group Messages

My Cheer coaches make a cheer group chat with 6 other people and they keep making it and i keep not receiving any of the messages, when i tried to make the group chat myself it wouldn’t even let me send a message into it? i have MMS and Group Messaging already turned on and everything and it still doesn’t work, only 1 person in the group has something other than an iphone and this group has worked everytime before.