Problem uploading resized images

I have a problem uploading any images that I have resized. I have actions in Photoshop that will auto create reduced image sizes from an original and if I try to upload these to any of my sites they appear in the media library as unlinked and do not show. I have tried resizing with different software, deactivated plugins and tried it on fresh install of WP.
It is baffling. Any ideas? Could it be my hosting? I have exhausted all my ideas. I have also tried it in Instant WordPress on a localhost and the problem still occurs. I have tried different browsers and different PCs and laptops.

Any help would be appreciated. Has this happened to anyone else?
Gordon