Zombie pigman not re-aggroing in Realms

When building a Zombie Pigman XP farm (Ilmango's farm: https://www.youtube.com/watch?v=4PWSUU9SFX0) I noticed that whilst the farm works perfectly in singleplayer, It does not in realms. I have double and triple-checked my farm using Schematica mod, and it's built properly. What happens is this: I shoot an arrow or throw a snowball at a pigman, and all the pigmen pathfind into the killing chambers, as they should. Despite 16 satellite pigman around the farm, which are still aggro, have direct eye contact with the player, none of the respawning pigmen become aggro,