Well, I had exactly the same problem here. I purchased truckloads of 25 packs of the old yellow label SONY8D1 and SONY16D1, and always had a PERFECT flawless Transfer Rate Test curve.
Last month a bought what seemed to be the same 25 pack, but got horrible resuslts at the end of transfer rate test, on ALL medias I burned, and even some read errors. After some scrutinizing, I found out they were made in Malaysia and not in Taiwan, like the old ones I had.
End of story: I returned all the 25 packs I bought, and traded for Taiwan Made ones! Guess what?? No problem with these!!
Bad story: this week i had to purchase more, and bought a 50 pack of so called Made in Taiwan ones, but without any label. Same error at the end of TRT scan....