Q: iCloud Photo Library albums not in sync with iPhone

I added 8 photos to an album on my iPhone 6S (not shared album). I charged the iPhone and connected it to WiFi to make sure all photos uploaded to iCloud Photo Library (I purchased 200GB storage space and am only using half of it.) On the iPad side (charged to 100%, connected to WiFi) all photos downloaded but the album only contains 1 photo. The other 7 photos are downloaded but they are not in the album.

So the albums are not sync'd properly -- I noticed there are some empty albums too where there should have been photos inside. Logging onto icloud.com also reveals they haven't been uploaded properly from my iPhone. How can I fix this? iPhone has already been updated to the latest iOS 10.0.2 (14A456).