After 7 years, a bug which causes some Trash Mobs to be removed in Darkheart Thicket Mythic+ has finally been fixed.
Darkheart Thicket was a dungeon from the Legion expansion. This expansion also included Dungeon World Quests and Mythic+ for the first time which were a great success and have carried on for multiple expansions. However, one bug has been known for many years, ever since the launch of Legion back in 2016.
When the Darkheart Thicket: Mythana World Quest is active in non-Mythic+ difficulty, a pack of trash mobs were removed and replaced with Mythana. However, this World Quest also affected Mythic+ difficulty — while Mythana didn't spawn, the pack of 4 mobs never spawned. This bug has carried over for 7 years since the Legion expansion, and throughout Dragonflight Season 3, whenever this Val'sharah World Quest was active, DHT was just missing a pack of mobs that players could use for count.
The timing of this World Quest showing up also happened to line up with the MDI this weekend and this inconsistency means that teams are unable to practice the dungeon until the World Quest is gone (3 days). Thankfully, this appears to have been fixed last night in Mythic+ difficulty.
The other bug in Darkheart Thicket that players have been complaining about is the random spawns of Dreadsoul Poisoner or Dreadsoul Ruiner. It's completely random and changes from run to run whether a Poisoner or Ruiner spawns in each position. You can sometimes get 4x Ruiner and other times 4x Poisoner. The Poisoners can be super deadly because their Poison Dispel, Nightmare Toxin, will essentially kill targets if not dispelled. If you RNG a higher number of Poisoners then dispels, then that sucks.
It's unclear whether or not this has been fixed for the MDI as well.