I have synched my 910XT multiple times and I do not see my data in Garmin Connect since June 3. Garmin Express does prompt me to add my username and password repeatedly, which I have done to no avail. I don't have any history older than 30 days on my watch.
I am sorry for the troubles. There are files that need to be deleted from the computer then you can resend the activity from the 910XT. Please see the two FAQ's below.
How do I remove FIT files that fail to sync in Garmin Express from my computer?
Once the files are removed from the computer you can resend the activities from the watch. If you have activities on the watch that are already uploaded to Garmin Connect we suggest you delete them before resending.
How can I resend my history from my wireless ANT+ watch to my computer?
If you continue to have trouble, please contact Garmin Product Support by phone.
