I attempted to import new photos into my library. Seems LR stopped responding. I tried to close it. I got a mssg if wish to close the import diaouge. I did. Tried again the next day, and LR does not see the photos in the folder any longer. They are there. I moved photos to new folder, and LR cannot see that folder in the source panel. Any way to reset the photos to never been imported?
Would suggest you to click on source drop down menu and choose other source and pick that particular folder from the finder/file explorer.
Let us know if that helps or if you need any further assistance.