I've been places and talked to people but the quest won't activate. I've done most of the triggers mentioned in the Fallout wikia. The only time I got a reaction out of her, that I can remember, was in vault 11, which is *not* mentioned as one of the triggers.

However, I've been to some of the places before I got her as a companion, and I've also already been to Hidden Valley and done some BoS quests, including putting that other guy to power. But some were new, the first time I got the confession out of Anderson she was with me, and I got no reaction. (Come to think of it, the reaction I did get from Veronica in vault 11 is the comment the wikia says she gives in reponse to Anderson, the one about having resources but no cause.)

(The first time I played the game I had no problem activating the quest.)