I'm having a bit of a problem, most images don't save despite getting the Best Ending and other stuff. I keep going back to the few unlocks.
ah, this is the first time I've heard of this issue! What system are you using?
In any case, right click on the game screen and make sure to allow save data to be written on your computer!
Hope this works! Otherwise, you could try it on newgrounds. It requires their plugin, but it might bypass the error you are getting. You'll probably have to start over though, sadly :(
In any case, I can send you the debug menu cheat on DM if that's ok with you. There's no "full gallery" cheat, but at least should help out a bit.