I think there's a slight irony in that the OP seems to have been extremely polite to everyone at QR, and perhaps this is why they spent 90 minutes doing everything to get him onto the flight. It's conjecture, but if the OP had been rude or unpleasant I imagine they would have sent him away swiftly, which would have meant him having enough time to cancel and claim an FTV.

Could the OP's politeness have cost him the FTV? You may say it's super unlucky for the OP.