im not sure then the only one i dont have in my gallery is one of asumi. You did complete her romance? Its towards the end of the game she'll invite you to bed.
unfortunately might have to un install the game and re download. Have you tried re downloading and hitting the folder again so it "updates". May just be some glitch that missed some coding. I honestly don't know sorry.
Random questions did you choose shaved or natural? If you chose shaved maybe that could be an issue. I chose natural.