Based on 1.11 decompiled using MCP 9.35 rc1
The bug
Some non-interactable entities like area effect clouds do not override the method net.minecraft.entity.Entity.canBeAttackedWithItem() to return false. This results in the sounds for the sound event entity.player.attack.nodamage being played and the held weapon having to recharge even though you cannot attack the entity in any situation.
Affected entities (vanilla)
These are the entities which can be punched using a vanilla client.
List might be incomplete, last updated for 1.12
- tnt
Affected entities (modded)
These are the entities which can be punched using a modded client which ignores if Entity.canBeCollidedWith() returns true.
List might be incomplete, last updated for 1.12
- area_effect_cloud
- egg
- ender_pearl
- llama_spit
- potion
- snowball
- xp_bottle
- dragon_fireball