This is a long shot on whether it might apply to you...
I purchased a 2013 Volt new and had an issue with XM traffic from the go that my dealer and other contacts from GM were never able to solve. Essentially at some point the all just gave up and offered me a few hundred dollars as a gesture. I live in Las Vegas, never had the car outside the county to see if the issue applied more generally. What happened with me in short was my Nav Traffic would not work UNLESS I first programed in some particular location sites (for ex UCLA in CA would work for some odd reason, dozens of other local or east coast sites would not). So each trip I would enter UCLA as a destination, wait about 20 sec for the green highlights on a couple major highways to appear, and then cancel the destination. At that point, XM traffic would be fine. But I always had to start with this odd first couple of steps. We discovered this work sort of just by accident.
I now have sold the Volt for a 2017 Bolt. The traffic info from Apple Play is a ton better (and free) than what XM traffic gives. I would not recommend it as worth paying even just a couple dollars for.
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