Lightroom deleting pictures from catalog when I try to relink/locate them

For some reason, Lightroom lost the links to all my pictures in the catalog. When I go back to locate/link them, instead of automatically linking all the images in the folder like it usually does, it just deletes all of them from the catalog. It did this before and after the most recent update. Files are in the same folders they always have been in. Any ideas on how to fix this?