I'm currently struggling with the same issue (and some issue with the menu map). I tried "Evil NPC" and "0", of which both didn't work.
Take a npc and put the alignment to 0 = enemy.
When you say 0, do you mean input the number 0 or just delete everything in the textfield of Alignment? I tried that as well and it didn't work.
And another question: What is the alignment of your player character? I suspect it to be relevant for this and maybe this is what I lack to get it working.
As a test, I set it to Hero Player1 and then to Hero Player2, but that didn't work either.
Maybe it's because they're taken due to Scarlett and Roderick being in my mod? (I still don't know if I can safely delete them :X).