This has been driving me crazy – I’m running an IMAP migration for one of our clients, and the batches don’t appear to have been running their regular incremental sync (by default supposed to run every 24 hours).
After digging around in PowerShell cmdlets trying to see if I could find a way to determine the last synced time of a batch, or even restart it and force a sync, I came across this article from Microsoft Support: http://support.microsoft.com/kb/2805982
Basically, the Last Synced Time status doesn’t accurately represent the most recent sync time of the batch:
Here’s how you check to see when your migration batch actually synced last:
Click on your migration batch and then click View details on the right:
Click on one of your users, and then read the details on the right, and you’ll see when the last successful sync happened:
This is actually pretty important to do, because I found a number of users whose status was Incremental failed even though the overall status of the batch was synced. This just goes to confirm my feelings about IMAP migrations – they are definitely the very last on the list of migration options, and I only do them if there are no other viable options.