Mark, I have never seen it either.
Here is exactly what I did.
About 500 from arrival I initiated three steps down ( 2000 at a time )
Vnav controlled. The CDU page in Vnav went to CRZ DSC like it should.
And then 50 from TD, I went to Vnav page 3, and pushed DSC NOW.
This triggers a shallow dsc of -1250fpm until you intercept the forecasted descent path. the aircraft should then resume that path.
My aircraft did not react to that and carried on the dsc at -1250 all the way. ( it would have been even worse) In a sense, my fuel saving worked. I improved by 1000 lbs. About 40 from arrival, I reset my MCP
to the ED alt of 2500. The airport alt is 10 !!!!! and completed the flight.

The intercept angle to the runway heading should be 30 deg or less.
The CDU should have an advisory message "LOC CAPT ACTIVE"
The aircraft is approaching the turn to the loc heading on course.
If the heading is modified outside the range of capture, New message
"LOC CAPT CANCELLED" reajust crs to correct.
If Vref speed has not been selected with add. new advisory message
"APPROACH VREF NOT SELECTED" input the flap setting and the landing speed.
I dont know if CS has programmed these messages, but they would be helpful to the new captains or FO in training.

Mark,  wise after the fact.  Last night I was watching a Postseason baseball game while I was reading bits and pieces of my flight manual
in the FMS section. in between innings.
I found this  ILS LOCALIZER FALSE COURSE CAPTURE
Loc false crs captures can occur when the beam and the airplane approach to the beam mis-process the deviation signal.
The false course capture is identified on the ND MAP.
Recovery
Deactivate LOC/APP.
Use HDG SEL to carry on to the runway heading to intercept
Verify proper indication in RADNAV
Rearm LOC/APP to capture proper loc crs.  ;D

Happy flying  8-)

Raymond   Boeing or nothing
KFLL South florida