Photos appearing on iCloud.com dont ever sync to device

I have a 200GB iCloud account and sometime around the start of iCloud Drive I synced all my photos from my 64GB iPhone 5S. Now I only have photos since last November on my device (570 Photos) and Photos app says 671 to upload, 466 to Download. I have 175GB Free on my iCloud account.

The iCloud drive *is* updating new photos, and are almost instantly available on my iPad (3rd gen 64GB) and Mac (2012 MBPr on latest OSX), but none of the pre-November photos download there either.
I *can* download them *individually* from iCloud.com, but for over 1000 files it's a bit tedious and RSI inducing, as theres no select all option.

Anyone any ideas how to get the photos back to my iDevice/Mac so I can back them up locally?

Also there seems to be an app on my mac that appears in finder called iCloud Photos but is only 1kb and doesnt launch. Could this hold the key?