Mobs with passengers that are slimes or magma cubes can't move and don't function correctly

The bug

When a slime and magma cube rides on a mob can't move and its AI will freeze causing it to not attack and spin.

The ridden entity will not attack or move.

Steps to reproduce

• Use the following command:

  /summon minecraft:horse ~ ~ ~ {Passengers:[{id:slime}]}

  /summon minecraft:horse ~ ~ ~ {Passengers:[{id:magma_cube}]}