I've had a little trouble from time to time getting sync to start with my FR220, and have had to unplug and replug it to get it started.
Last night I was doing this, but once when I unplugged it, it seems that the sync had just started as I unplugged it, and then every time I plugged it in again and pressed "Sync Now", it would look like it was starting to sync (rotating icon appearing next to the "faded" Sync Now button, but no green line appearing at the top of the screen), and just hang. (It failed to actually sync, although I left it for hours.)
After quitting and restarting Garmin Express, and unplugging and replugging the FR220, and also turning the FR220 off and on again, I tried uninstalling and reinstalling Garmin Express, which worked! The next time I plugged the FR220 in, it took several minutes to sync (longer than usual), but it did work.
Given the hassle, I thought it might be helpful for someone else in the future! :-)
Happy running!