Hi,
I was using commands to try and put a Shulker on a villager's head, and the shulker started trying to teleport away, but it looked like it was forced to keep riding the villager. It was really buggy, and the teleportation sound kept playing on repeat.
1. Load up any world. (I was on a super flat)
2. Enter this command; /summon Shulker ~ ~1 ~ {AttachFace:0,Riding:{id:"Villager",Profession:0,Silent:1}}
3.See the glitch.
I attached a screenshot, but it is much, much, much worse in the actual game.
The Shulker is a block mob, and if it isn't attached to a certain surface, it teleports to one. but the stack keeps it from moving, so it gets sent back. it tries over and over again, as you can see (and hear, too. ik, it's annoying).
putting "NoAI:1" on it would stop the freakish teleporting, but would remove the need for it.
Plus, if the villager moves, the shulker tries to stick to it's current position, twitching rapidly (causing seisures to the sensitive eye).
aye, jus' surf ye Shulk's features in data tags on ye's web for ye to hopefully understand ye Shulk's meanin'.
(Pirate for: "just look up the Shulker's data tags on the internet to hopefully understand the reason.")
All in all, this isn't a bug's fault, but the mob's type itself.