How to trigger download of thumbnails of icloud photo library to iOS? After uploading a large number of photos through the web upload of iCloud Photos my iOS does not show thumbnails of those new pictures but a grid of icons with small clouds in it.

It has been like this since two days now. It seems the only way to get the thumbnails downloaded is to look at every picture on my iOS device.

Is there more efficient way to download thumbnails? (Preferably in the background)
The only way I have found is to click through each one. I usually start at the top and swipe through them, and they should start downloading.