Hello,
I had never had any issue with syncing and general use of my forerunner 910XT.
However yesterday I tried to normally update 2 activities from the weekend, but I could not get it on Garmin Connect. They won't show.
Also I noticed that in my profile my device is shown as unknown. On Garmin Express everything seems fine, it recognizes my 910XT and apparently the transfers are being done.
Any thoughts? I note that I tried to do the syncing on 2 different computers, but the problem remains.