[1.9,1.10,1.11,1.12,1.13,1.14,1.16] Many recurring issues with /tp facing @p

Verification Build: 1.10.0.0 Beta, 1.9 all builds (pretty sure all of them anyway)

Partner Rank: 3

Summary:
Starting in the first beta of 1.9 and continuing to 1.10, there have been many issues with teleporting entities to face the player using "/execute @e[type=X] ~ ~ ~ tp @s ~ ~ ~ facing @p" on a repeating command block.

These have morphed over time in their symptoms and behaviors throughout the development of 1.9 and in 1.10.

For the purposes of this bug report, I will be focusing exclusively on the behaviors observed in 1.10.

1.9 Behavior varies greatly.

In 1.10, the primary issue seems to be that entities have a massive (and greatly variable) delay before they actually turn to face you. It seems they like to ignore you for a bit. Some entities exhibit this behavior while others refuse to face you at all. Sometimes it only works occasionally. It doesn't seem to follow a specific pattern. Some entities there are no issues at all.

Impact:

Many of our maps that rely on characters interacting with you are not functioning properly. Models appear to glitch because of it. Maps lose a lot of their effect and immersion.

Repro Steps:

1. Create a new flat world
2. /give @p repeating_command_block
3. Place down the command and paste this in: "/execute @e[type=!player] ~ ~ ~ tp @s ~ ~ ~ facing @p"
4. Place a redstone block next to the command block
5. Summon various entities and walk around them to see their behavior.

Observed Results: 

The following were all recorded in 1.10.

Entity: Witch

Observed Behavior: At first it seems to work but then when I approach the tree she seems to ignore me and there is a long delay before she turns to face me.

Video of Behavior: https://youtu.be/JGzqzA0lgDo

 

Entity: Horse

Observed Behavior: Again, very rarely it works as expected but as you can see in the video, there is often a very long delay before the horse decides to face me.

Video of Behavior: https://youtu.be/Ld0MBKE56I4

 

Entity: Zombie

Observed Behavior: Expected Results until the end of the video where the zombie on the right decided to look off to the side briefly.

Video of Behavior: https://youtu.be/akrmo_MDaG0

 

Entities: Many

Observed Behavior: As you can see, throughout the video, the behavior varies greatly. For some entities they don't ever even attempt to face me. For some, like the llama, they will face me sometimes but other times freely look around. It should be impossible for them to look elsewhere at any time while having this command run. Sometimes an entity will face me properly but have a long delay before they do. I think the gist here is that these behavior are unpredictable and inconsistent and rarely behave the same way that they used to. Once again, in 1.9 these behaviors are slightly different but still do not consistently behave correctly.

Video: https://youtu.be/P3UnCBXekr4

 

Expected Results: 

In 1.8 and below, the expected result is for an entity's head to be LOCKED onto you with its facing direction, then within the next second, the body would follow the head to also face you. Since the command is running every single tick, this behavior would make sense. No matter where you move, the entity turns continuously to face you. If an entity is constantly having this command run on them, then it should be impossible to look around other than directly at you. In addition, once the entity has come to rest at a specific rotation, the legs should now stop playing the walk animation. This is how it used to behave in 1.8 and below.

Screenshots/Videos attached: 

Yes, many.