In some cases, he Order Contact or Billing contact fields are missing from the Back office Checkout screen. This only occurs when $0 tickets are added to the order.
Our team is aware of this issue and determining a fix. The release date for this fix is still to be determined.
The user can first add a payable item to the order which will make the contact fields appear as expected. Once the contact fields are populated, the user will remove the payable item and replace with a $0 item as desired. This will retain the contact information and the desired tickets for the order.