If it's the right jcv file [D3191090A.JCV] for the NA 2014.10 map and it must be if it was working before as 3760, then there is no good reason why the exact same map & jcv file won't work with the unit converted to 3490. Those described paths are correct too for the unit and card. It doesn't matter if the jcv file and map are both on the unit or card, or one is one the card and the other on the unit. I don't know what to suggest other than are you sure you've tried a route with JC views available? Try a simulated route from the center of NY City. Select New York, NY from the top of the list [Press Where To?>Categories>Towns>Enter Search>'New York'] and then set that as your location. Then repeat for Buffalo, NY as a destination. There are heaps of JC Views on that route.

Otherwise, redownload the JCV file and replace your current copy. Maybe it's been damaged somehow.