Same here. I’ve killed tons and gotten the collar off of each. I also didn’t get my silver bars for the halfway mark. It said there was an error with the event. Now I can’t make anymore progress. The same thing happened with the widow maker mission. I brought the truck to the stop point and it bugged out.
In case your hunting wolves and not getting the collars, check to see if you accepted the challenge at the Start Menu ( Continue, New Game, Arcade.... )
Choose the Advertisement window on the right.
Accept the challenge from the new window that appears.
Start hunting the wolves with Arrows..
I have had collars drop when I get the kill, but no collars dropped when my Friendly or Fanf for Hire kills it,
No collar when the wolve dies from Fire, Bats, Bullets, or Friendly.
Wild wolves or Peggy Wolves count toward the challenge.
At 5 collars, you'll get a message on screen that you have a reward waiting, and at 10 collars you'll get the same message.
Pause the game and choose the Adverttisement window to see your progression and Accept the rewards from that window.
Just thought I'd clarify how to do the challenge because I thought I could start hunting wolves but I was getting no collars either...but I did after realizing I didn't even accept the challenge.
Note that the collars will take a moment to count towards the challenge because of lag ... but they will count eventually.