Just did it, same thing. Also if I connect using Garmin type instead of Mass storage device, I'm getting a message that the following items cannot be transferred: -waypoints, -routes. I did a master reset and my problems are still there.
I also tried to update my Eastern Europe map (released today, version 3) with Garmin Express. Firstly I used Garmin Type connection, but Garmin Express gave me a message: Update Failed. Then I used Mass Storage Device connection and the update succeeded.