The Garmin Connect site won't download all the data from my Garmin. It has downloaded only the activity from August 26th to the present. All data before that (from June 13th) is on there, but no maps or details of the rides. It is still on my Garmin, and it is also in my Garmin Training center - but it won't download it from the Garmin Training center either!!
Check out this thread. Most likely your oldest activities on your device are being overwritten, leaving only summary data. This is because your device has limited capacity (13,000 trackpoints) and newer activities will overwrite detail data on older activities. If you've uploaded to MB, then your best bet is to wait for the migration to complete. Additionally, I suggest you make it a habit of clearing out old history from your device once you have uploaded to GC and TC. In your case, you definitely want to delete activities before June 13th.
