I tried the first 2 options - did not work. I also tried option 3 and another handful gallery apps - all inferior (advertisements, poor edit, poor display options, no move function) compared to Galaxy built-in. Last resort i did this: Settings > Applications - pick Gallery app - memory, click 3dots at top right corner - uninstall updates, revert to factory version All blank/black photos reappeared. This shows there is nothing wrong with our internal storage (or SD card). Neither are files corrupted. Problem lies with bugs in the new gallery software update.