At the bottom of 'Photos' in my photo app, there is some status text that says
35555 Photos, 2152 videos, 1 item Uploading 244 Photos (12.1MB of 389.3MB)
The upload starts when the Photo is running in the foreground.
However if I switched to another app and back, the uploading line will become:
Uploading 244 Photos (0MB of 389.3MB)
and slowing climbing back to the previous high watermark.
I think these 244 photos are waiting for upload for at least a week now (since I last take note of the text)
How can I make the Photo app to continue even though it is running in the background?