Since PhotoKit framework has been introduced by Apple in iOS8, and all ALAsset stuff became deprecated in iOS9, it's safe to say this will never get fixed.
This can, however, be done properly with the new PhotoKit API's.
You have to set the networkAccessAllowed = YES
on the PHImageRequestOptions
when asking for an image, and it will download it from iCloud if needed.
PHAsset* photoAsset = ...
CGSize fullImageSize = ...
PHImageRequestOptions* options = [PHImageRequestOptions new];
options.networkAccessAllowed = YES;
[[PHImageManager defaultManager] requestImageForAsset:photoAsset
targetSize:fullImageSize contentMode:PHImageContentModeAspectFill
options:options resultHandler:^(UIImage *result, NSDictionary *info) { /* use result image */ }];