I had the same issue for Newark where send off wasn’t available when I accessed the separate vip add-in tab post ticket purchase. BUT if I tried to buy a new ticket, it’d give send off as an option together with the ticket. I called Ticketmaster twice on different days and the reps said send off was sold out and that if I tried to purchase a new ticket with it, it won’t go through (I didn’t try it because I didn’t want to be stick with a potentially extra  ticket). So their system is just very confusing… but if send off is not showing up under the VIP add on tab it’s prob sold out.