I'm not sure what happened to ETMY SUS, but it was in a pretty bad state. Bad burt restore, I would guess.
Most egregiously, the inputs to all of the coil output filters were switched off. This is a bit insidious, since these inputs being off doesn't show up on the overview screen at all. This explains why ETMY had not been damping for the last couple of day, and why my binary whitening switching measurements were nonsense.
I also found that ETMYs damping filter was a 30 Hz high pass, instead of the 3 Hz high pass in all the other suspension controllers. Unfortunately a messed up burt restore can't explain that.
I normalized the ETMY controller to match all of the other controllers (ie. gave it a nice new 3 Hz high pass), adjusted gains accordingly, and now ETMY is behaving nicely.