A new version of Audacity just came out - maybe it was today. It's version 2.1.2, and it's the first version meant to deal with Windows 10 - although it may require a sound card driver update.
So, I installed it - and I can once again record direct from my computer. I haven't been able to do that with Audacity since I had Windows XP. I had a workaround - plugging my Zoom Handy H2 recorder into the headset jack of the computer - but it was awkward. Now it seems to work just the way it should.
Hooray!

-Joe-