I had a panorama with 10 images, and then I used auto crop, which worked as expected. I then removed 2 images, and used auto crop again, however this second time instead of selecting the area of the image which one may expect it to, it instead selected a long thin area - it seemed to have the correct width but not the correct height. I am assuming that it is something to do with needing to remove the images before using the auto crop, however it seemed slightly odd behaviour based on what can be seen in the preview.