I have the same problem, and am at the same decision point ( cancelling family map). I bought this to track my son as he goes back and forth to school so I know he is safe. If it is not going to work on the iphone then I want a credit. It has not worked since he got the 6 about 3 weeks ago.
I suspect this is something Apple has done, likely to not allow tracking without specific permission each time, but this negates the purpose of the app for me and I am am sure for many.
AT&T if you care about your customers you need to come clean and explain the problem. If you just do not know, can I suggest you call Apple!
We are waiting for an answer and most of us are likely running out of patience.