I tried all sorts of suggested fixes online:
- reboot (MANY times!)
- ran WindowsUpdateDiagnostics tool
- ran System File Checker (SFC)
- Reset the content of the Catroot2 folder
There were other more-involved fixes, too, but I wanted to avoid them if at all possible. I mean- this was a brand-new install so how could any system files have gotten corrupted? I hadn't had crashes or other errors before this point.