iCloud photo library on iOS 9.0.1 only uploaded when screen is on and photos app is open
I'm having the same problem, except that no even opening the photos app makes the photos upload. They just won't. The iCloud > Photos tab on Settings just says "Low Disk Space - Uploading 20 photos" and it never shows a progress bar or anything. I have selected "Optimize iPhone Storage" because I'm obviously low on space. 

My understanding is that you might need to clear some more space for the "optimization" to take place.

Open Settings App - under Storage &amp; iCloud usage - compare the Used/Available numbers with Photos &amp; Camera storage used currently. If you have less than 1 GB available, try clearing other data and then powering off and on the phone.


under Background App Refresh - consider turning that on before the restart above (or another restart) in case Photos respects the global refresh settings.


A more drastic measure might be clearing all photos and letting the phone try to start over with no photos, but depending on how large your library is, that might take some time and battery and network bandwidth to download.