Justlink not activating [Nero 6]

My DVD burner [nec nd6650] suddenly started making coasters on multiple media types so I paid more attention to things during the burn process, eventually realized that Nero was not activating the Justlink buffer underrun prevention. Usually the 3rd or 4th line to pop up on the progress screen was “Justlink Activated” , now it’s not showing up. Double checked in the burner options menu and it is enabled.

Any clue what would cause Nero to stop activating it?