I have also just run into this issue, same situation. I suppose I could just switch companions going forward but I'm pretty attached to my walking, punching meatshield.
It is apparently a dialogue bug (essentially, when you exit dialogue, she... doesn't.
So a somewhat drastic measure that fixed it for me is the console command 'rdf'.
This is drastic because rdf apparently can't be targetted at single NPCs. It will 'reset dialogue flags' for ALL npcs, everywhere.
What that essentially does is it makes them react to you as if you've never talked to them before next time you talk to them. Except for those NPCs you have outstanding quests with (those will address you appropriately to the quest, which is why it fixes Veronica). However, this only counts, near as I can tell, for the first time you talk to them after you use the command, they will offer you quests again, but if you've completed that quest already, just give any response that doesn't automatically make them attack you and then they'll simply go back to knowing you completed their quest.
So it's drastic in the sense that it'll give the whole of New Vegas temporary amnesia.