Initial synchronization gives you possibility to synchronize (migrate) Jira Issues and TFS / Azure DevOps (formerly VSTS) Work Items that were created before TFS4JIRA Synchronizer has been installed.
You can only start one initial synchronization per profile at a time and you have to wait for the initial sync to end before starting a new one.
Starting the Initial Synchronization
At this point, the initial sync will begin in 15 seconds and the issues starting from selected during which you have an option to cancel the operation clicking the "Abort" button.
Once the initial synchronization is tarted, the issues between start date and end date will be moved to the corresponding project.
Note: a limit of 30.000 items applies to a single Initial Synchronization.
If you want to sync more than 30.000 items, please run separate initial synchronizations with smaller time ranges.
This limit is temporary and will be increased in the future.
Once the Initial Sync starts you will see the synchronization status and ultimately - an Initial Sync summary, showing how many items were synced succesfully and if there were any errors:
You can view the details of initial sync clicking "See Details" button in Profile Events