My phone updated GCM to 4.15 this morning, and 4.15 won't allow Livetrack unless you also allow Garmin to suck your contact list down to their servers. With 4.15, if I start GCM, tap on the three bar menu, and tap on Livetrack, I get a screen asking for permission to store the contact list on their servers, and if you tap "Don't Allow", Livetrack can't be used.
I can't see any valid reason why this should be necessary, and plenty of reasons why it's a bad idea and invasion of privacy.