Email Address blank for Lead details using email template through workflow

Using Advanced Open Workflow 2.0.1 and SugarCRM CE 6.5.17.

Trying to create a send email action type of workflow for newly created Lead. I have created a email template as below:
A new lead has been created in CRM, details are as below:

Name: $lead_name
Email: $contact_email1
City: $lead_primary_address_city
Lead Source: $lead_lead_source
Description: $lead_description

All variables are working fine other than $lead_email1. It is showing blank even if email address has been added to Lead.

I had used the ‘Email Address’ option from the ‘Contact/Lead/Target’ module option in Email Templates to select email address.