So, I bit the bullet and got a new MBPr on the cheap since I needed it. I have the Photos app set up as follows: iCloud Photo Library (✓) optimized for storage, My Photo Stream (✓), iCloud Photo Sharing (✓). Most of my photos and videos have synced fine, but it's been stuck at "Downloading 108 items" for 2 days now. Storage space is more than sufficient, wifi connection is fine, battery charge is fine, and I have tried leaving it plugged in over night with and without Photos open. Any recommendations as to what is going on and how I can get it to download the remaining items?