You sure it's across ALL saves? This only happens to me when I reload from an Autosave point - whenever I reload from a save I've made myself this issue doesn't appear.

Check your Anachronox\anoxdata\SAVE\<"Username">\photos folder ("Username" is the name you chose in Anachronox as your profile name - if you don't choose one it's "GLOBAL"). There should be a directory for each save, each of which containing a bunch of TGA and DAT files named photoXX.tga and photoXX.dat, where XX is the position of the photograph in the camera.

If these folders are all empty or contain no TGA files then your photos are indeed gone. Unfortunately, as far as I know there's nothing you can do about it, unless you can restore the deleted files somehow...

With those "collection" quests (e.g. Bipidri pics), whenever you're near the guy you hand them in to, if you talk to him you'll get all the new pics "marked" as complete. While with the Bipidri guy you don't get anything until you have all the pics, once a Bipidri is marked as complete it doesn't matter if you lose the photo later as it's already "done". Which means less frustration and repeated effort if your pics disappear mysteriously.