The bug

Hoglins don't indefinitely attack non-piglin mobs that attacks them. If they can't reach the target who attacked them, they'll just give up and walk away.

To reproduce

1. Build a fence
2. Spawn a Johnny vindicator
3. Spawn a hoglin (with or without IsImmuneToZombification)
4. Wait for the vindicator to attack the hoglin
5. Use the following tp command to teleport the vindicator outside the fence:

    /tp @e[name=Johnny] @s 

6. The vindicator and the hoglin runs close to each other in the different side of the fence
   → Eventually the hoglin loses interest on killing the vindicator while the vindicator that's named Johnny still wants to kill the hoglin

Video

Minecraft 1.16.1 - Singleplayer 2020-07-08 11-23-52_Trim.mp4