Unable to Retrieve line items from a CRM invoice

Unable to Retrieve line items from a CRM invoice

Hello,

I am trying to setup an integration between Zoho CRM invoices (not finance module) and Xero, which basically updates in realtime on invoice creation or invoice changes. I have setup a webhook from Zoho CRM that fires to Integromat which then sends to Xero, however the webhook payload does not include the invoice line items. 

How do I make the webhook fire with the line items?
Webhook Fire > Upload into Xero

Or alternatively, how can I retrieve the line items via API? I have tried using the subforms setting but that is not working either. This is the workflow I have tried
Webhook Fire with Object ID > Make an subform API call using the Object ID to retrieve line items > Upload into Xero