Was having the same issue. I was using a USB 3.0 burner that was only powered over USB. Once I plugged it into a powered USB 3.0 Hub (it was the only thing on just in case), it worked perfectly. I was on a MacBook pro, and did not have anything plugged into the 2nd USB port but it seemed after about 5-9% of burning the drive would stop the write light flashing but would act like it was still writing.