iCloud Photos not Syncing with iPad

The photos from my iPhone stopped syncing with the iPad a week ago. I logged into icloud.com and I see the latest photos from my phone there, so I've ruled out the phone or my iCloud settings. My iCloud settings are set to sync photos. I tried all the standard steps to fix this problem (restart iPad, reset network settings), however it still won't sync.

If I open Photos in my iPad, I see the spinning wifi circle indicating it is doing something over the Internet. However it doesn't say anything like "Uploading X items". If I leave it for a while, nothing seems to be happening.

Any ideas on how to fix it?