Try change you computer.
I was REALLY hoping that, if I killed the monsters, the software could manage this for me.
This worked for me.
Already talked about it here. I have about 200h of gameplay with my Desktop, no legendary. About 100h with my notebook, 10 legendary, 1 every 2 act3 runs.
Yesterday I tried the PTR with my notebook, 3 legendary in less than 2 hours.
You may laugh, or you can try, it's up to you.