Webform2pdf and CiviCRM fields: pdf empty
In a Webform, CiviCRM fields are webform fields. There is no difference as far as Drupal is concerned. The only exception is CiviCRM credit card fields (which you really don't want to store in the webform submission).
The "existing contact" field is another special case, but although it gets processed a bit differently it is still a "real" webform field and ought to work fine.
So aside from the above I can think of no reason why any CiviCRM-related fields would not appear on a PDF.