This issue expands on the previously reported bug MC-165448. While the original report cited broken pathfinding for Wither Skeletons due to constant NBT updates, my comprehensive tests confirm that almost all mobs are affected, with varying degrees of AI failure.
The trigger command I used (executed via a repeating command block, 20 times per second) is:execute as @e[type=!minecraft:player] store result entity @s attributes[{id:"minecraft:scale"}].base double 0.05 run data get entity @s Health
Note: The purpose of this command is to create a dynamic visual effect where mobs gradually shrink in size as their Health decreases when they take damage.
The resulting AI breakdowns fall into the following 5 categories:
Normal pathfinding, but cannot update the look-target in real-time (every tick):
The mob can pathfind and attack normally, but its line of sight fails to track the target accurately on each tick, resulting in a deviation in visual aim.
Affected Mobs: Zombie-type mobs, Creepers, Spiders, Cave Spiders, Phantoms, Vindicators, Ravagers, Iron Golems, Polar Bears.
Sub-variations: Witches, Evokers (while casting), Pillagers, Blazes, Drowneds (holding tridents), Snow Golems, Llamas. When the target is within range, they completely fail to rotate their view towards the target while attacking.
Note: For Zombie-type mobs holding spears, the issue does not cause a complete miss; rather, the charge damage calculation is affected. I suspect that the failure to update the mob's line-of-sight/aim in real-time prevents the game from correctly calculating the relative velocity factor for the charge damage mechanic.Almost completely unable to pathfind, but can still perform basic melee attacks:
Affected Mobs: Skeleton-type mobs holding melee weapons.Normal pathfinding, but completely unable to shoot:
Affected Mobs: Skeleton-type mobs holding bows.Almost completely paralyzed (unable to pathfind, turn, or attack):
Affected Mobs: Endermen, Villagers, Piglins (no matter what weapon they hold), Piglin Brutes, Hoglins, Zombified Hoglins, Goats, Axolotls (still able to play dead), Copper Golems, Armadillos, Sniffers, Creakings, Wardens, Breezes, Nautiluses, Zombie Nautiluses.
Note: Most of these mobs rely on the "Brain.memories" AI system. Piglins and Hoglins will repeatedly spam their anger sound loops.Almost completely unaffected:
Affected Mobs: Cows, Sheep, Pigs, Chickens, Wolves, Horses, Donkeys, Mules, Dolphins, Pandas, Zombie Horses, Skeleton Horses, Happy Ghasts, Camels, Camel Husks, Bees, Wandering Traders, Slimes, Magma Cubes,Sulfur Cubes, Ghasts, Illusioners, Vexes, Withers.
Note: Their target tracking fails similarly to Category 1 when they are attracted.
Steps to Reproduce:
Set up a Repeating Command Block with the following command:
execute as @e[type=!minecraft:player] store result entity @s attributes[{id:"minecraft:scale"}].base double 0.05 run data get entity @s HealthSpawn any of the affected mobs listed above near yourself in Survival mode.
Move around and trigger their pathfinding/attacking behaviors.
Expected Result:
Mobs should be able to perfectly track targets and execute their AI loops, even if their data is constantly updated by command blocks.
Observed Result:
Mobs experience various types of AI paralysis, ranging from inaccurate line-of-sight tracking to total loss of pathfinding and attack capabilities.
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