Hi
I am having the same problem!! With 398 genuine images loaded, after “Smush”ing them, I now have around 5000+ images. I believe after upload, (or is it after “Smush” that images are stored in the MySql database, which is why you can’t find them.
After a little research, I found a plugin from “PimWick LLC”, that is supposed to find all the unused images, and then give you the opportunity to delete them. It certainly found around 4700 “Unused images”. Having paid around $20 for the “Pro version”, or whatever it is, you then have the opportunity to “Backup” the images before deleting them, but after clicking the backup button, you are advised to look at your website to ensure all is still well with it, before actually deleting anything. This warning is just as well, because the plugin removed a number of “Category” images from my site, leaving only the descriptive text below the image in a box that previously contained image and text.
Retyrning to the image cleaner, I then “Restored” all the various sizes of one particular image as a test. Unfortunately, the image in question had not reappeared, when I looked at the page containing it. It was only after restoring all 4700+ images that I was able get my page back to normal. Of course, the same Pimwick Plugin may work fine on your site – I just do not know!
I believe there are several other plugins available that will clean out the surplus images that are generated in a seemingly chaotic fashion by WP Smush”, if you go down this road, use them with caution, or you may wreck your site
Hope this helps
Julia