@Tech@ZWO#58470 Yes, I checked all possible places in the device manager where I thought it might show up. As a test, I also plugged/unplugged a Starlight Xpress Lodestar X2C camera; I could see it appear and then disappear in the device manager for both the PC and in the System Report in the Mac. After plugging in the ASI120MM, I also did a "Scan for hardware changes" on both the PC and the Mac, just to be safe, but there was no change.
The problem occurred after running FW Update using a Windows PC. I didn't disconnect or otherwise interrupt the update while it was running. I do remember seeing a message saying something like "you can reset the camera now". (Not sure exactly what it was.)