Photos library sync failure

I use iCloud to sync my Photos libraries across my Mac, iphone and ipad. I noticed that my iphone immediately syncs changes that I do on my Mac (e.g. deleting a picture) but my Ipad doesn't follow. I can add/remove/change albums but no changes seen there. It is the same iCloud account and there's enough space left on the device.

Any suggestions? Can I force a sync?