Thanks, @leroydouglas.
System software is already up to date -- Venture 13.2.1.
I've already tried re-indexing. Not clear whether it actually happened based on my watching Activity Monitor data.
A few other details that might be helpful:
When results in the Spotlight window aren’t clickable, they have a generic MacOS icon rather than a folder icon or the appropriate icon for the document type.
Also, if I scroll down to the Search in Finder option at the bottom and click on that, the correct result shows up in the new Finder window and I can click through there. So Spotlight's index seems to be correct, but something else is going wrong.
Thanks again for your help,
Andrew