iCloud photo library not all downloading
On both my iPhone and my iPad have iCloud Photo Library enabled and I have it set to "Download and Keep Originals".
My iCloud Photo Library is set to is 8.1GB, and my iPhone and iPad both have more than that free, but both devices have downloaded about 5GB and then stopped. When I go into a photo then they often have to download it before I can see it at full resolution - and if I have no internet connection I'm shafted.
They are both 128GB devices with over 10GB free (and that's on top of the 5GB of photos they are already holding) so there's plenty of space.
Does anyone know how I can get it to download the entire library to both devices?
This may or may not be related to this other issue where it is intermittently incorrectly telling me I don't have enough space for my photos: Re: Not Enough Device Storage - Full Resolution Photos - Wrong!
Thanks for any help
Dan
iPhone 6, iOS 8.1.3