Then I encountered a bug.

Either Scarlett's personality was set to "Random" or the "Free Spirit" personality doesn't work as intended (in some dialogs).
I'll try to reproduce it and send in a savegame...
Did you checked the resulted traits? At replay I stopped bother about traits, but at first play during about half of the play I did and quoted multiple traits bugs. Sometimes it was even same trait result for opposite choice involving a dialog combat mini game.
Also sometimes I quoted result traits was hard to link with the dialog choice.
As AI personalities are linked to traits results if this results has bugs the personalities will seem have bugs.