Apple - iCloud Photo Library not fully syncing on iOS
Turn your iPhone off and the back on. If that doesn't help, disable iCloud Photo Library and then turn it back on. If that doesn't help, logout entirely out of iCloud and then re-enable it.
Turn your iPhone off and the back on. If that doesn't help, disable iCloud Photo Library and then turn it back on. If that doesn't help, logout entirely out of iCloud and then re-enable it.