Unable to consolidate Invoices for multiple Sales Orders of Template Type "IN".

Hello,

I am trying to consolidate/combine Invoices for multiple Sales Orders through “Process Orders” screen. The Sales Order Type is of template Type “IN” that does not require Shipments.

Important to note that Avalara is the Tax Provider. 

This functionality out of the box works fine when I don’t have Tax Zones. In other words, if there no Avalara involved, the Invoices are being consolidated through “Process Orders” screen. However, when I apply the Tax Zone Avalara, the system is creating separate Invoices for each Sales Orders. 

Note: Each Sales Order has different Ship-To Address. I believe this is the reason. 

Has anyone faced this issue? Any advise will be very helpful!

Thanks!