So I will keep this quick. I dis find a resolution but i wanted to put this out there just incase someone might have the same issue.
I was working on my challenges and came across the first Hammerlock hunter challenge. I nearly killed the beast before she made her first transformation, though as she was set to turn into her little pod, she vanished. I tried for days to go back and kill this beast. But she never spawned. No pod. Nothing.
At a loss for what to do, and with few friends I waited till a friend made it to true vault hunter mode ( they refused to go back to this map until they finished). I hopped into their game where the beast spawned every time they walked into the area. And I killed this beast here (with my friends help). This was the only way I could complete this challenge and get 100% for the challenges.
So incase this happens to you this is what worked for me. If this can be fixed without going into another game that would be great.