Inside LeadsTunnel's campaign level, you should see the number of leads received by LeadsTunnel under Form Leads. If the number has a discrepancy with the leads on your Facebook Lead Form, you may click on the "Retrieve" button under Form Leads to retrieve the missing leads.
Please note that the retrieve button will pull all the leads saved on this Lead form from your Facebook account. You will also need to click on the "resync" button to sync this missing leads to your autoresponder once you have retrieve them from your Facebook account.