Kind of random, but the Bounty “Kill Thugeesh the Enraged” which takes place in the Unknown Depths in Act 2, the four of us scoured every pathable space and were unable to reach the 100 kils.
Some of those maps in Act II have chests which, when clicked to open, spawn four mobs. Bounties should not be made so that clickable spawns are required, but this might have saved the act / cache for you if that’s the case.
I run nemesis bracers to spawn extra.
While this may make some bounties quicker to complete, it should not be a requirement for any bounty. All bounties should spawn with more than enough mobs to complete without requiring specific gear.
Think about it… Tyrael says there are 100 mobs in a level that are pestering the townsfolk, and sends you to kill them all. You kill 99 mobs clearing the entire level, and return for your reward. He tells you you needed to spawn extra mobs and kill them too before you get paid.
Did Tyrael lie about the number of mobs in the level? Wearing Nemesis bracers were never part of the bounty contract.