I haven't been able to sync for about 4 days. Today I tried multiple times with Garmin Connect Mobile, on both my phone and laptop, then downloaded Garmin Express. Garmin Express told me it's been a long time since I logged in, and had me reset my password -- 4 days isn't that long. Now it synced, but has lost everything I've recorded for that past two months. I also was prompted to enter a display name... which seems to be due to a systems update.
Seems like I have a new account.