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The problem with it is actually from the reveal guide cheat, as it was flagged to only appear once, and used the guide progress as a marker of having seen the scene.
In cheats you can reset guide progress and the scene will then work. This also effects Lina's moonstone, but should otherwise function completely normally.
I have also fixed for future versions this bug so that it is more robust.
Also if you to look for a guide look here
https://nunushouse.com/cbtl/index.php/Sami
If you specifically want to know about her moonstone look here