After an update to MacOS sierra, my BMW Navigator wasn't detected anymore, neither by Garmin Express nor by MacOS itself (as pseudo-USB-disks).
Solution: Borrow a Windows PC somewhere and install an firmware update on the BMW Navigator once. After that, the BMW Navigator gets detected by MacOS and Garmin Express again, and you can return the windows PC.
BTW: German Product Support was not helpful at all in this case...
Merry Xmas everybody!
