I was equally frustrated. I was doing it with all three every week since it was announced. Saturday I was on and during a run party chat, random player told me to complete all other bounties. So spent Saturday completing bounties until all I had was the one for ice breaker. Went in and first character landed the ice breaker. Was it just time? Was it because I was on my fifth run with the character? Not sure but got it and I credit the fact it was the only bounty on the character. Good luck