QuickBooks > Synchronize, and click on the Sync Now button right beside the label of Full Synchronization.
If you are already in Method, you can go to
Also, you may want to see if the Customer has synced over, but is hidden. Go to Customize > Integration Tools. Select 'Export a table to a file'. Then pick the Customer table. Follow the instructions to produce a file where you can check if the customer is indeed in Method.
Let me know if this helps.