More technical difficulties

I streamed as usual Saturday. I did note from the summary afterwards I hadn't gotten watched nearly as much as I was last week, which felt sad. But it didn't feel like the drop needed a real explanation; viewership still was about at the level it's often been at during the month I've been doing this now.
Then, while preparing for this morning's stream, I took a look at the video, and discovered OBS has suddenly stopped picking up the desktop audio! No wonder my viewership dropped. Honestly, I'm a little surprised I apparently still got 35 minutes worth! I kind of wish one of the five presumably non-scamming viewers who came in and out at various points according to the summary had pointed it out, but they might have even thought I'd turned the audio off on purpose. That's far from unknown on Twitch, though usually the streamer then turns music on.
I was forced to let Windows update Friday morning, and I'm pretty certain that's the cause, and that they turned something off in the settings. Unfortunately, I current have no idea what. I've posted in the OBS discord and hopefully someone will tell me by Friday, although my streaming then was up in the air even before this.
ETA: Figured it out on my own. This time.