I started a large import overnight. The import apparently finished by sometime mid-morning while I was away. However, Lightroom didn't start doing its indexing task, apparently because of the dialog on screen indicating a few possible errors that may have occurred during the import. Apparently, Lightroom felt like it had to wait for that dialog to be acknowledged by me before it could begin its indexing task.
So instead of a completed import, I now have a large group of images that still have to be indexed. That's 24 hours for one import SO FAR, and it's still not done! Lovely!