If you are receiving leads but they are shown as N/A, it is likely that the Facebook account you have connected to LeadsTunnel does not have the permission to access the leads from the lead form. In order to have access, you will want to ensure that you are an admin of the Facebook page. Only admins of a Facebook page is able to access the leads.
If you have confirmed that you are an admin of the Facebook page but the lead is still shown as N/A, then, you will want to check in the business manager admin account of the Facebook page and ensure the Facebook account connected with LeadsTunnel has lead access to your Facebook page. For more information, you will find this Facebook article helpful.