Invoice PDF layout Shows Blank Line Items

If an Invoice printed in PDF doesn't display line items even if set to Standard form or Custom form, perform the following:

   1. Navigate to Setup > Company > Printing & Fax
   2. Go to Printing tab > Transactions section.    
   3. Unmark the Print Transactions Forms Landscape box.
   4. Click Save.

Standard Invoice is set to be fitted in a Portrait format.