Sometimes zombies cant walk over rails. They walk up to them and stop and stare at me...
MC-55878
Rails And Mobs
Resolved
Duplicate
0
David Gartner
(Unassigned)
Unconfirmed
Minecraft 14w21b
Retrieved
Intended.
While not an official source, the MC Wiki states that "mobs no longer walk over rails unless they are pursuing the player."