Zombie Pigmen attack without provocation

Problem: Zombie Pigmen attack without provocation.

Likely cause: Zombie Pigmen hit by attack from hostile mob such as Blaze or Skeleton Archer. Death of attacking hostile mob causes Zombie Pigmen to attack the player.

Another user has had the same problem and has detailed the issue here: https://www.youtube.com/watch?v=vokGKpkYV_Q