A custom data sync operation is a process that has been created for your organization by Blackbaud.  Most of the time these processes are scheduled to run regularly (daily, weekly).  To determine for sure if you have a custom data sync operation navigate to Import/Export under Data Management menu within Luminate Online.

 If you cannot access the Import/Export page, your administrator does not have the appropriate permissions to investigate the answer to this question, and you will need to find a site administrator at your organization to check this.

You will be presented with the Data Sync Operations tab where both standard and custom synchronization operations are listed.

Custom data sync operations created by Blackbaud will only have two available actions: Run and Last Result.  All operations created by administrators on your site will have additional options (edit, schedule).

Once you locate these operations, you can view the last run time to determine if the operation is still in use.  If the operation has been run recently you have an active custom data sync.