We are aware of an issue where vibration alerts are being turned off after syncing with Garmin Connect. The engineering teams are actively investigating this issue.
We apologize for any inconvenience that this has caused in the mean time.
EDIT** A fix was implemented in Garmin Connect that will prevent the vibration/tone alerts from being turned off on devices that have the ability to manually adjust this setting.
A fix for devices that do not have a manual setting for vibration/tones is still being worked on, in order to resolve this issue fully.
***EDIT*** The full fix for this issue has been deployed to Garmin Connect. Users that have the option to manually enable the tone/vibration can adjust the setting on the device.
Devices that do not have a manual tone/vibration setting can sync with Garmin Connect through Garmin Express or Garmin Connect Mobile to re-enable vibration alerts.
Again we apologize for any inconvenience that this has caused.