You said you tested this right? I move to Hellfire and fire it up, it collects "I work.. For the horde" and also picks up "Bonechewer Blood" - but then when it heads out of the town to turn in "Eradicate the Burning Legion", it gets almost to the quest guy and stops - saying in the HB log: "Activity: Setting Infernal Rain (Hellfire) at xx yards as your target!" and then just stands there. It does this over and over again, inching closer and closer to the quest guy - once it finally gets to him, it will click on him and do what it's supposed to.
I guess I'm just wondering if it's something that needs to be changed in the Profile to make it not try to target inanimate objects, or if it is an HB bug,.