Background:
-2 weeks ago (6/11) I used my Garmin 910XT during a long trail running activity.
-The event took me ~14hrs, and I didn't notice anything suspect with Garmin operation during activity.
-After completing the activity I performed the "reset" (save data) function without any visible issues.
-Under "Mode-History-Activities" on device, the full description of the activity is visible (total time, total distance, calories, pace, etc.).
-Had to go out of town and didn't attempt to upload data from watch to Garmin Connect until today (6/26).
-Garmin connect says "sync completed" but also shows "some files could not be uploaded to Garmin Connect, you may want to manually remove these files from your device.", and a single file name is visible (date and timestamp correspond to ~1hr after I completed the activity, perhaps when I reset/saved data).
Troubleshooting:
-Under "C:\ProgramData\Garmin\GarminConnect\Forerunner 910XT-3910197441\FIT_TYPE_4", there is a single 444KB .FIT file. Based on previous long-duration activities, this file size is small (e.g., a 9hr event has 703KB file size). Also, the "date created" value for this file is 6/26 (today), not 6/11 (the date the activity was recorded).
-Attempted manual upload of this .FIT file to Garmin gives "An error occurred with your upload, please try again".
-Attempted manual upload of this .FIT file to Strava is successful, and shows data for the first 5.5hrs of activity, which is consistent with file size discrepancy.
-I tried the "Mode-History-TransferAll" option on device to see if this recovers missing data, this was not successful.
-Under "C:\ProgramData\Garmin\CoreService\Devices\3910197441\Sync\FIT_TYPE_4" there are some files with "date created" timestamp close to my "TransferAll" attempt (28 files, ~3MB total), I think this may contain the data I need, along with some older files that seem to have been re-transferred.
-Under "C:\ProgramData\Garmin\CoreService\Devices\3910197441\Sync\FIT_TYPE_9" there is a single file with "date created" timestamp on 2/9, but modified on 6/26 (today), 1KB size.
Questions:
-Any suggestions on how to recover the full data for this activity?
-Any suggestions on whether I did something to cause this issue? For example, I do not delete old activities, I just let the device overwrite old data with new. Does this cause problems with new activities with large amount of data?
Please let me know if additional information is needed.