We confirmed this tonight. When attempting to add a second prompt to a dialog prompt trigger, the game crashes to desktop.
Put an object on a map.
Put a dialog popup on a map (the blue talk icon in the map builder)
Create a simple chain of dialogues in the popup by using the advanced dialog editor. It could be something like Hello ---> I like trees ----> I like big trees. Basically, you need to make the prompts.
Now, go back to the object. Set it to become visible when dialogue prompt reached. Select "I like trees." Now, click "add prompt."