The bug
Mob AI ignoring damage dealing blocks when randomly walking around/not fleeing when hit by them.
Affected blocs
Cactus
Magma block
Lava
Fire
Wither rose
Berry bushes
Campfire
Example
Here is a great example:
[media]Linked issues
is duplicated by 33
relates to 9
Attachments
Comments 36
Confirmed for 1.1, and also for magma blocks.
This still happens in 18w31a.
Confirmed for 1.13.1.
Can confirm for cows in 1.13 with lava.
@unknown Do you have any reproduction steps you could supply for this issue, since you just confirmed it?

Place a magma block 3 blocks in front of the player and 4 more blocks (2 extending left and right each), then lure a villager with food.
Observed result: The villager takes damage from the magma block.
Expected results: The villager can path find around the magma blocks to go towards the player.
Also speaking about villagers, I want to highlight a few other serious bugs:
*Particularly important
The villagers pathfind around the magma for me, and doesn't take damage. If I close the food in with magma blocks they will just stare at it. Do you have any other reproducing steps?

I can't reproduce this in 1.21.3 and 24w45a either. Attached the image.
Closing this ticket as cannot reproduce.
Still happening in 1.8. One of my important pre-1.8 villager just died from a cactus.