Hello,

I see a couple things with the screenshots you sent.  I need to attach other screenshots so I will have to spread across a couple replies.  The screenshot is from the default template you can download from QuickBooks Online.

1. There's no need to have the mapping fields listed across multiple line items.  You only need 1 row of each mapped field. Item, Description, Rate, QTY, etc.  

What you want to do is edit the line on the tabel to make sure its marked to Resize Line to fit contents.  That way when you add a 2nd line to the invoice, it will automatically add another line to the table.