Can't turn off screen lock

After running some miscellaneous update, my MacBook Pro (15-inch, 2016) now requires me to enter my password when I wake the computer up after the screen saver starts. I cannot turn this off in the Security & Privacy preferences panel - I unlock the panel, uncheck "Require password after sleep or screen saver begins," I get a dialog box asking, "Are you sure you want to turn off screen lock?", I click "Turn Off Screen Lock", and it goes back to the panel showing the box checked again. I also can't change the delay for enabling the screen lock - whichever duration I choose, it goes back to Immediate.

Any thoughts out there?

Tom