If your media is not uploading properly, it's probably due to one of the following two factors.
1. Your network connection is being interrupted. Please connect to Wifi and try your upload again.
2. Your screen is going to sleep while the upload is in process. To avoid this, tap your screen every few seconds as your media is uploading, or you can temporarily set your phone to not go to sleep. You can do this by going to Settings, then Display, then Screen Timeout and then selecting "Never Turn Off." After your media upload is complete, you can readjust the sleep settings.