I recently created a project with two chunks and a few dozen photos per chunk. After importing photos (but before alignment) I thougth that maybe I should try to process all images as one chunk, so I just moved all photos from the second chunk to the first, using drag and drop. Suddenly, the photos which had been moved did not have camera information anymore ("NC" after the file name), and when I tried to align photos, no alignment of any photos was done. I had to remove the "NC" photos and re-import them (then they did not have "NC" anymore), and afterwards all images were aligned without problems. I think something goes wrong during drad and drop.