Prior to patch 2.4 the range limit was that they had to be "visible" to your character (which I believe was a fairly large distance as long as they were in the same zone). With patch 2.4, they have to be within inspection distance for you to see their talents. There is nothing we (authors) can do to get around this.
Personally I think they should still allow you to see talents for grouped members as long as they are visible. But I'm not sure who to complain to :(
They also changed it so you can't inspect hostile enemies (PvP). This is what broke addons like Proximo from detecting talents, and they also force you to treat your own character "player" differently then other units in 2.4.