CP is correct that the iPhone must be in the foreground or the transfer will terminate before all of the Camera Roll is updated. Here is a post I wrote a long while ago describing how to keep the iPhone in the foreground during uploading:
As for starting over. The MC app creates a default folder on the MC device to place the download into.
You can find this folder and either rename it or delete it, so a new folder of same default name is created. In my case, I renamed the folder to a similar name so that when I had success uploading the complete camera roll I could compare the two folders. I eventually deleted the first folder, and kept the second, successful folder of all the camera roll contents.
