HomeKit no longer talks to HBB

I'm afraid there are several variables involved here, plus this has been happening for at least a week and I jut haven't had the attention to put into troubleshooting this until now.

While I've seen occasional errors in the Indigo log about HomeKit Bridge having to shut down, when I look at the HBB logs this morning I don't see anything that jumps out at me as an error, though the logs are very dense in general and I could be missing something. I've tried all the applicable Advanced options in HBB with no effect I can see, and no change in function.

The biggest change I can think of is that around the time things stopped working, I upgraded my HomePods to the current OS that comes with iOS13. But I'm not at all certain these actually happened at the same time.

Siri works for any native HomeKit device, and fails for all HKB devices. Same in the Home app.

I'm at a loss on how to troubleshoot this, after having restarted everything, including the Mac Indigo runs on.