In case anyone was wondering what happened, Asus said that my drive was defective and I had to send it in for repair, because they couldn't reproduce the problem on their end. That's AFTER numerous emails where I finally convinced them that the drive actually supports BDRE-XL. When I asked them if they tried the same model disc as I used when they couldn't reproduce the problem, they didn't respond.
In the end, since my drive was out of warranty, I didn't send it it because I didn't want to pay for any "repairs" they might do (or $35 on top of shipping for them to just look at it). Luckily the seller on eBay that I bought the disc from gave me a refund because it didn't work.
I guess no one was really happy in the end here. But at least it wasn't because if IMGBurn.