When editing a picture in an outside editor, the view in Lightroom is updated automatically after finishing the external edit. This is true even if you think the image hasn’t changed.
I use Photoshop for spot removal on negative and slide scans. I also use Photoshop for some specialized sharpening.
The problem is that after removing some additional scratches on a particular image in Photoshop and returning to Lightroom, the scratches were still showing. I tried deleting the library views and refreshing them. The scratches were still there.
I experimented and found that I had merged layers above the healing layers. I had sharpened that layer. Unfortunately, that layer then had a copy of the scratch in it, so the final image still contained the scratch. I deleted the merged layer and then recreated it and sharpened it. The scratch was gone.
After saving the file and returning to Lightroom, the scratch no longer appeared. Thus, the two lessons learned: 1) review all the layers in photoshop when makeing changes and 2) remember changes are immediately updated in Lightroom.