I don't know whether this is simply a coincidence or if it's cause and effect. I updated to the latest version of Jetpack and activated carousel. Almost immediately, one of the photos in my media library disappeared - more precisely, it disappeared from pages that linked to it; in the media library, when I tried to access the file I got a message that said it was damaged.
I re-uploaded the file, updated all the links, and deactivated carousel and all is fine for the moment.
Is it possible these things are related, or just a coincidence?