My husband and I both own garmin 310xt. Last night my husband tried to upload his recent runs using Garmin express. It kept coming up with "re-authentication required for account". We tried the workaround we found on this forum (deleting the sync folder) and thought we might try uninstalling and reinstalling garmin express. Now we can't get Garmin Express to add either of our devices. We have tried using different ANT sticks, we have tried different USB ports, turning the watches on and off and restarting the computer.
Any ideas? We are very frustrated