Saved a bunch of images from email and copied to Photos. Brought up the Photo app, Downloads shows 12 images, life is good. From the computer I moved those images to a new folder. On the phone, tossed the Photos app and relaunched it. Still says that Downloads has 12 images but if I go into it, it shows 12 empty thumbnails. Rebooting the phone fixed it (Downloads drawer does not appear since it is empty). Apparently the app is maintaining some kind of state somewhere - anyone know where? (i.e. what to do to fix this without rebooting?)