Update: this looks like user error—I goofed. The Novoflex adapter has a ring that can force the diaphragm open and this ring has a range of turning. If that is off just a little distance the wrong way, the lens does’t stop down fully—I had it maybe 1/4 of the way to "open". I wish there were a lockout mechanism, because I prefer to control the aperture using the aperture ring.
Issue: the Novoflex Nikon F Lens to Leica SL/T Camera Body Lens Adapter
cannot reliably stop down the lens past f/8, and even f/8 might be iffy once in a while.
The coupling for the adapter is purely mechanical and since it is hard to believe that my Otus is at fault (zero issues for years on Nikon cameras), I blame the Novoflex adapter. But whether it is this particular sample of the Novoflex adapter or a general issue, I don’t know.
Jason W writes:
If the Novoflex adapter doesn't work I'm inclined to throw out all ideas of purchasing a Panasonic S1R.
DIGLLOYD: the Nikon Z7 is a better platform with far superior lens adapter; I would go with the Z7 if the goal is Zeiss DSLR lenses.