Some recent locks have had steeply downward-trending ranges, which seem to be due to a steady increase in jitter coupling.

I hadn't seen anyone say it explicitly, so I decided to check the cause of one of these drops in range. I picked the lock on Oct 15, where the detector was in intent mode around 19:30, and the range had dropped 20 Mpc by 20:30. I ran Bruco at this later time (Bruco results page).

Above 200 Hz, all the coherences are with ISS PDB, IMC WFS, and the like, suggesting that jitter coupling is steadily increasing (and I think there's no feedforward because of issues with the DBB). Attached are the h(t) spectrum and the change in coherence with PDB relative to the start of the lock - the spectrum of PDB and the WFS don't change.