When sufficiently far from the center of the world, mob pathfinding appears to break down significantly such that mobs swiveling on their own accord is a common occurrence. This appears to affect the majority of mobs.

1. Spawn some mobs reasonably close to the center of the world, e.g. striders in lava
Note that their behaviour has pretty much nothing out of the ordinary.

2. Spawn the same mobs 17 million or more blocks away from the world's center
After a while, the mobs should start rotating completely by themselves for no apparent reason