So you're probably seeing behavior from the app that looks like it's not uploading in the background because you launch the Dropbox app and watch it upload your latest images. However, I can tell you from what I see we are getting some background time on your device and appear to be properly uploading photos when new ones are available. This background behavior is very sporadic and much of it is likely to happen when you're not using your device. This way, it doesn't drain your battery or slow down your phone when you are using it. If you need something synced right away, the only way to be sure it happens is to launch the Dropbox app directly.