The auto-uploader has stopped working for me as well. Also, when I share over 1 GB of photos and videos to upload manually (as a work-around), the upload stops at various amounts of data uploaded. The app basically becomes useless at this point; no manual upload (files still queued, but never finish), no auto upload. The only way I can get any other upload activity to uninstall and reinstall the app.
I am using a Samsung Galaxy Nexus, running Android Icecream Sandwich (4.0.2).
We were able to improve upload behavior on 1.3.1 (by fixing an upload resume issue on our side) but it is still erratic on some handsets due to a bug in the Android Connectivity Manager. We wanted to take the time to make sure we have a solid workaround for this OS issue and are planning to include it in the next major update.