When I got the bike home, I de-greased the rear cassette. At the same time, I obviously tightened the skewer adjustment bolt. A LOT. I did loosen it afterward, but my thinking was "this can't be right, I shouldn't have to loosen it this much".

Well, this morning I did the measurements, loosened the bolt further, and presto! The wheel goes back on.

Dumb, dumb, dumb.

But, all's well that end's well, too.

Lesson learned. Thanks to all for your help.