Here's a short list of achievements that cannot currently be attained in the game due to bugs or oversight:
Almost - Kill a monster with your orb that would otherwise destroy your orb Orb damage was removed in a recent patch
Flea Trap - Kill 45 cursed monsters with your orb Orb danage was removed in a recent patch
Put the Lights Out - Gain 500 xp from destroying beacons Beacon XP does not increase the counter for this achievement
Bone Shredder - Kill 600 monsters before wave 12 starts The bar counts up, then keeps counting past 600 without awarding you the achievement
Stormy Weather - Have the beacon storm trait set to Level 7 at field N7 N7 does not exist, probably due to the bug with the third compass reward
Lockpick O4 - Destroy all wizard locks at field O4 before wave 18 starts O4 does not have wizard locks. O6 does, but doing this in O6 does not award the achivement