Killing the hunted NPCs does not yield a quest update or item drop which allows you to turn it in with the Muster
If you don't speak to the NPC, the head won't spawn. That's intentional!
I've spoken with him first and they still did not spawn.
I haven't done it recently, but about a week ago I was able to claim a bounty without actually talking with the Musterman beforehand. The head dropped, gold was given to the head holder, and experience was given, but there was no quest logs involved.
What VP said.
I've seen the bug where you talk with the bounty with the "[Approach]" dialogue option and nothing happens.
Yes, I've also added a requirement for having seen the bounties, because you guys were murdering them without actually knowing there was a bounty. Tsk tsk.
I'll double check for the head not dropping.
To be more clear, I spoke with the Musterman, clicked the bounty boards, and then approached the bounty for no effect. After that, I tried just attacking him and he did not drop the head item.
By "having seen the bounties" do you mean walking into the room where the bounties, actually clicking on them, or right-clicking and examining the boards?
Tried it today. Went to the muster NPC and spoke with him and even clicked the signs, no head dropped after I beat the bounty npc.