I have an update:

I ran into this very same issue again today, but this time the computer won. I tried the above solutions, as well as every single other fix I've read or thought about, and the disk is still pegged at 100% at all times.

I eventually left the computer with a chkdsk running because I had to get going. This one was super frustrating. Clearly Microsoft has a problem here, and I haven't seen anything to indicate that they know about it. I see a lot of different computers in my daily work life, and I've never seen anything hit so many systems at the same time.

The fact that it's happening so close together also has me wondering if it could be related to Windows Update. The anniversary update went out recently, and I wonder if there was something about that? I have no idea. At this point I'm just thinking out loud...