Pi5 audio oddities

A Pi5 running bookworm has suddenly lost sound. The last update
was a couple days ago and seemed unrelated to sound in any way.

Right now audio output is via "Digital Stereo (HDMI) Output".
There's no sound from YouTube or the New York Times and I still
hear a burp when I power cycle the speaker system, so the analog
side is alive. There's also a small chirp when I power-cycle the
HDMI monitor, so I think the HDMI-audio splitter in the display
is alive.

Right clicking and holding on the speaker icon at the upper right
of the screen displays HDMI and Device Profiles, but both seem
greyed out.

Anybody seen this sort of mischief?

Thanks for reading!

bob prohaska