The phantom group message

Ever since I got my IPhone 6, I've had this issue where some group text messages show up but as opposed to naming a group of participants like Richard, Cathy, Chris, James and Frank it instead shows up as "unknown". The issue is not who is on the message because you can sort of figure that out as each person gets noted as they send out some type of correspondence but the real issue is that you cannot reply.
So there might be a conversation going about a chart of female body parts but there would be no way for you to correspond to give your 2 cent input.

Even pressing details on the top doesn't help

Apple, fix this mess