im having the same issue

i actually had delta manually issue the ticket and VN is saying they see the flights on the e ticket however i dont have a reservation on the flight.

one segment is air France and that shows fine on airfrance.com along with the Vn flight

delta is saying they can only refund the miles and tax they cant get a seat on VN

SOMETHING IS VERY WRONG

delta.com was not showing any availability however today 3 seats are showing.

any help would be appreciated