i tried that. Uninstalled the device and now my Fenix 2 isn't being recognized by Garmin Express at all. This is quite frustrating for such an expensive product to have to put so much time into it for a basic feature.
I worked with a original fenix and a fenix 2 on a iMac. With the fenix, I was not able to sync with Express until the software was up to date. Skip the sync step in order to add the fenix to Express, then do the software updates to the device. After the software is up to date then try syncing with Connect.
Instead of choosing "Yes, Link to Connect" click "Do This Later".