I've got a bizarre problem with a website I'm working on.
Recently, when anyone uploads images to the site, some time later (maybe an hour, sometimes several hours) one or more images disappear from the server. They still show up in the Media Library, and all the other sizes created by Wordpress are still on the server. But whatever size is being used on the page (usually the full size image, but not always) randomly gets deleted.
If I replace the missing file via FTP, they tend to disappear again fairly quickly (sometimes minutes, sometimes hours later).
I've tried removing any plugins recently installed. No luck.
I've even migrated the site to a completely different server. Oddly, it seemed to work at first. For several days, I had the site on the new server and no images disappeared. But then, once I updated the DNS settings to point the domain over, then they started to disappear.
Neither hosting company had any clue what could be causing it.
Have you ever seen a problem like this? Any idea what function I can look for that could be deleting images at random?