Slime Passengers always Direct their Mounts Towards (0, 0)

I summoned a whole ton of zombies, each with a slime in their {Passengers} tag. Be because of the new AIs with passenger mobs controlling their mounts, slimes will always direct their mounts towards the coordinates, (0, 0). I would like to be able to put slimes on other mobs' heads, so please fix this. Below is a screenshot of many zombies wearing slimes on their heads, all moving towards (0, 0), regardless of entity collision.