P: Batch save to device at 2048 pixel resolution for non-contiguous selections.

Yes, your method works! I can set the parameters as you mentioned. Many thanks, very helpful. 

Yes, I can see the problem when the selected files are not contiguous, which looks like a bug to me.

However, rather than using "Export as..." you CAN use the "Save copy to device" share option....that does have the settings icon at the right hand side, use that first to set your export parameters (Jpeg, 2048px, etc.). That option does allow multiple non-contiguous selections to be saved to the device.

I just tried again. First I selected 5 images and the option save images above the Print was available for 5 images. Then I added 5 more images, making the selection 10. The option save images to device disappeared. It is very inconsistent, I still hope this is a bug, rather than a limitation to few images... 

This is interesting. As you say, it shows up in some situations. Right now I was able to give the option save 5 images for instance. However, when I randomly added more images from the middle of the album, the save images option disappeared again, leaving me with all the other options only. Try to test it. Keep deleting different numbers of images, more that 5 or so, randomly. It is highly inconsistent for some reason. 

Sorry, my first response was a little incorrect, as I mistakenly thought you were using the Android version, which works the way I described.

However, the iOS version has the same "Export as" option, but that's even better on iOS as it has all the expected share destination options as well. I've just tested it again, and I can confirm that when you have selected multiple images, then used the Share icon, the resulting sharesheet includes the simple "Save xx images" option (above the Print option), which does indeed save the images to the Camera Roll.

Yes, but for a single shot only. If you select several photos and click in export as, pick the small 2048 resolution, there is no option to save to device photos all those images. There are options such as save to files, etc. So the batch saving at 2048 is missing in my opinion, which slows down my workflow. 

Using the "Export as..." sharing option still allows you to set a custom resolution yourself (there's even a "Small (2048)" option). "Export as...." only saves the exported file to the device gallery (there are no other share options), but it sounds as though that's all you need.