What kind of database are you running on? MsSQL, Postgress? I case of MsSQL you could try to see if the MsSQL analysis server is tracing any activities. You can try to run again, before you do the synchronization, you can check what synchronization statement is about the execute.
How much data do you have? If it's a local database there should not be much and updates should go pretty quickly. If your local data is not important or can easily be replicated you can also create a new database.