Looking at my notes for a now exchanged device I saw no mention of the SE device at first (near out of box) when I ran sleepstudy. Then the usual Hardware Video error showed up in Reliability Report and from then on the Unregistered Device was listed in sleepstudy reports.
I think this is all connected to SoDs, 327.67 errors, the SE device and Tegra drivers and/or hardware. We'll never know for sure.