Hi there…this quest is currently showing a visual bug for me (after multiple attempts). This bug did not exist before the patch, as I did the daily quest to whack gnolls the other night.
Basically, it allows you to hit a gnoll, but the gnoll will not be destroyed after you hit it with the hammer. So it remains up, while new ones spawn under them - making it quite hard to see the new one.
Just wanted to let you know 
Having this same issue, glad to know I’m not alone
Same here. I tried updating my addons (handynotes and tomtom) and I tried a ui reset. Didn’t work.
Can confirm the issue. Mighty annoying.
I’m also experiencing this issue. The game has basically become a game of “Memory”. Trying to remember which knolls I hit. Tonight, I hit one, but it was actually a doll, so I was dazed and lost time to hit other knolls. Nothing in the patch notes about this, and not really sure how an unrelated patch would affect just this game at the DMF, but please fix this!
Same thing. This patch sucks
Same deal. Sick of hitting the babies underneath a gnoll I’ve already whacked.
I reported this in-game also it’s bugged and I’m being sent here. I don’t use any addons and it worked fine until the update on Tuesday. Blizzard plzzzz fix this the Darkmoon Faire is almost over now ;(
I have been having this same problem. When whacking a gnoll, it no longer disappears in a flurry of leaves (or whatever they were.) Instead it stays visible until it eventually fades away. In the meantime, a doll or even another gnoll can spawn in the same barrel before it fades.
I run around whacking the same gnolls over and over hoping a doll isn’t underneath it.
This appears to be fixed now for me! And the “poof” animation appears better than before, but not sure. Thank you for fixing it!