I checked both scenes, and Alex's really had a mistake in the code and wasn't working in the gallery. I've already fixed it for the next version. Thanks for reporting.
As for Adriana's scene, there's nothing wrong with it, and it should work in the gallery once it's unlocked in the story.
But I need to make something clear so there is no misunderstanding regarding the functionality of the gallery. If you unlock a scene, it will become available in the gallery and remain like that even if you restart the game from the beginning. However, if you unlock a scene, let's say the one from Adriana's corruption route you mentioned, and then load a save before the decision to choose the scene from the non-corruption route, the first scene will no longer be unlocked in the gallery. This happens because when you load a save, it's like nothing you did after that save point ever happened.
That said, tell me if you find other scenes with the same problem, and I will check it. Maybe some of them have a small mistake in the code like Alex's.