I'm curious -- do your images come from an iPhone camera? Or, are your working with larger resolution images from another camera or source?
We're aware of an issue where large resolution images from 3rd party cameras may exceed the memory available to our app running on iPhone and iPad devices. This results in the behavior you describe.
The work-around we suggest is to use iTunes to import those images, and sync them to your iPhone or iPad. iTunes will downsample the images and make them more usable for our mobile editor.
Does this help?
I use a canon 500D and usually shoot on M size. I have been using PE for around 1 month for editing imported pictures from my canon 500D. In general, there was no problem "sharpening and saving with M size file pics" BUT recently I found the problem. Yes! It seems no problem with S size file pics but no more with M size. Why does it not work only on " sharpening and saving" while all other app functions still have no problem with M size pics. I use other apps like Photo Meta and Photo Sort.
Does the problem reproduce with the same images if you restart your device, and then go straight into the Photoshop Express Editor?
Why I ask is that we restrict our app to use only a percentage (but not all) of available device memory (i.e., RAM). Despite popular thinking, not all background apps release memory, so what we get from the device varies over time. That could explain why images that once worked no longer do.
Aside from that, my previous advice of using iTunes to sync those images to your device still stands as the best work-around. We are investigating ways of improving how large images are handled. Stay tuned....
Please try using sharpen with Photoshop Express 3.1.1 It provides an enhanced algorithm to sharpen your images and you may not face problems while saving them.
Hope it helps.