THIS ACTUALLy WORKS
I've been searching for an answer to this very problem for a solid day. Here is what I did that worked for me. No reset. No need to upgrade to more Cloud storage or anything else. I had already deleted out every picture from my phone, including "Messages" and the "recently deleted" album, etc. There really are phantom pictures in there, but the only way to see them and delete them is to:
- Go to Settings
- Date & Time
- Untoggle "Set Automatically"
- Manually change the date back. For example, if today is March 15, 2015, choose August 1, 2014. (You can change it back once we're done)
- Close out of that
- Open "Photos"
- Select "Albums"
- If, like me, you had already cleared out everything from the Camera Roll and "Recently Deleted" folder, you'll smile to see that your "Recently Deleted" folder now has thousands of images back. Those are your phantom photos
- Open it, "Select" and start deleting
- Now, go back into Settings - General - Usage - Storage - Manage Storage - and you'll notice your Photo & Camera is empty if you deleted everything
I hope this works for everyone and that I saved you all the time I wasted searching for an answer myself -- only to never find one. Now you have the answer.
I went from barely having any room left on my phone to almost brand new again.