Both clusters fixed!
I am pleased to report that BMW NA offered to replace both displays with missing pixels. It paid 100% of the parts, I paid 100% of the labor.
The 'catch' is that the job is to replace the entire dash unit as well as the center console device, costing about $270 in labor. The fix is *not* to simply replace the malfunctioning displays.
The unexpected benefit is that the speedometer is now more accurate than before.
As expected, as in as soon as I got it home a new problem presents itself, the 'Check Tail Lights' error message began to appear upon shutting down the car.
And, just today, the 'Low Coolant' error message appeared - now for the 2nd time. I guess I have the slow radiator leak problem.