UPDATE:
I did not have enough points for said tickets, as I didn't realize the amount it was charging was per ticket (silly me thought that if I searched for two seats, it would show me the total for two seats). It therefore defaulted to the points+cash rate. The kind crewmembers on Twitter helped me solve this. I just wish the website made this clearer, but (again) silly me for getting my hopes up for anything.
As an aside, it took 35 minutes, seven logins, and 10 searches -- all over two devices -- just to get to the checkout page.
-J.