If you experience syncing issues, please follow these steps to solve this matter:
1) Update Bookly to the most recent release;
2) Update the Redirect URI in Google developers console;
3) Disconnect all staff members and connect them back;
Doing this will most likely solve the sync issue. If it persists, or if for any reasons you can not update the plugin, please contact us at firstname.lastname@example.org for further assistance.